Security is important to a point, but even though one can imagine all the ways something can go wrong, one does have to weight the cost/benefits of implementing a lot of expensive (and often ineffecient) security to stop it.  

Let's expand on the WHAT IF scenario for a moment.  The plane example was mentioned already so let's add a few other examples.  What if said wife took the metro instead, and a similar scenario occured.  Or shopping in a mall, or taking the bus.  What would happen if we implemented similar security features in those places.  You have to take your shoes off, and have your bags checked, etc, when you went on a train, or in a mall.  After all, the safety of everyone is paramount, so we should do everything we can to make sure nothing like those could ever happen.  

I will grant you that a bomb going off in a metro train, or in a mall wouldn't cause as many casualties, but they would still cause some, and one of those could be someone's wife, someone's brother, and so on.  But what would the economic opportunity cost be in implementing said security procedures everywhere.  That's something that all too often is not considered, and I guess partly because it can be difficult to nail down the alternatives.  Are the billions that would be spent on such security (not to mention the massive amounts of wasted time that occurs for individuals everywhere to go through them, and time is a valuable resource as well) the best place for that money to be spent?  

Everybody can kill another person. Hell, you can kill fifteen people just by slamming your car into a bus stop.
Let's take all cars from everyone.

Taking my example into such a scale is exactly where your "cost/benefits" becomes extremely unfavourable.

An airplane is a very specific place. You can stop a bus and get out. You can stop a subway train and get out. You can't just stop a plane and get out.
Further - you can immobilize a bus or train and thus render it harmless by itself, to both the people inside and outside. You can't stop a plane.

There's no emergency break on a plane. The passenger has no control over a plane. Plus, crashing with a plane is a safer bet than using the emergency exit in air.

Of all the mass transit systems, airplanes are most dangerous if something goes terribly wrong and it is the easiest to make things go terribly wrong on an airplane.

Also, you're talking about "economic opportunity cost" of applying high security in every public place. There's no "cost" to discuss, there's a level of stupidity instead. You can't check every person in the world if he isn't leaving his house with a bomb in the bag. You just can't.
But you CAN check everyone who's getting on an airplane.
And it's being done.

Like N3Rull said, you don't have to power everything at once. And one more cool thing: The rails effectively don't need maintenance or repairs because they don't wear out: The train flies over the rails and never touches them.

I doubt that security will be much of a problem with any transportation method that can't be flown into skyscrapers.

The USA is actually ideal for the MagLev system (as opposed to Germany which developed that technology): Large cities seperated by great distance. Germany has lots of cities which are near enough to be easily reached by foot or bike.

But guess who won't like to see the MagLev being used in the USA. Yep, those that profit from the alternatives: Planes and Cars. Tough luck for Siemens ... they have a history of bribing the wrong guys.

Lul whut?! Near enough to reach by foot or bike? What, you expect people to walk for a couple of days to reach the nearest city? Quite funny in comparison to the USA, where people are too lazy to walk or cycle to the mall.

Ain't that Tarja on your Avatar?

If I didn't have to take off my shoes or take my laptop out of my laptop case it would improve the experience massively.

Yeah, right. Captured criminals would be that much happier without handcuffs as well.

All sorts of objects, from knives to bombs, have been brought aboard planes in hand luggage (laptop case?) and used to deadly effect a number of times in the past.
If you don't want to open your laptop case, rent a private jet/helicopter. They won't bother.

Oh and if you want to know why they're checking your shoes:

Yesh! that's Tarja.

It also has been proven that you can make weapons out of non-metals, explosives out of non conspicuous materials, cause considerable damage with liquids < 100 ml and if that doesn't scare you then you'll be happy to know that airport security is so arbitrary in some countries that you can just walk in there without being noticed.

You'll never counter all threats, you will only (try to) minimize them, but you can ask yourself if it is worth it.

Your wife can also die when walking your kid to school because some drunk thought he could still drive a car. Actually cars are more likely to kill you than a plane anyway (even if you can stop a car) so you have to ask yourself what the use of it all is. As a diabetic who needs to have some form of carbs with him at all times it's very frustrating to have to throw it all away. And because I'm not rich I fly cheap airlines which means I have to pay an arm and a leg for food inside the plane.

A little common sense would go a long way here. Personally I've stopped travelling because it's simply a pain in the ass.

I've seen grandma's in wheelchair's close to strip searched by folks with towels wrapped around their heads. I'm as much against racial profiling as the next guy but get real.

The TSA has no real effect other than give the *appearance* of safety. I’m willing to give up *some* freedoms if they really do have a positive effect but giving up my rights (and time) for the mere appearance of safety is silly.

You know, I could actually deal with the searching. I carry dangerous stuff with me but that's for my medical condition which I have a pass for, other than that I never did get manhandled so far. The most annoying thing here for me is the time it takes, omg.

However I'm increasingly beginning to wonder about privacy. Apparantly US customs are allowed to copy your entire harddrive of any laptop you carry with you, they want your personal information even before you enter the country and fingerprints are mandatory so I've heard. I'm sure most people will never have to worry about this but I wonder what on earth they intend to do with all that information. As if a terrorist is stupid enough to keep his I'm-gonna-KABOOM-barack-obama plans on his laptop he carries on him.

Every time I leave Israel security personnel at Ben Gurion question me for an hour.

I don't mind. I know why they are doing it and it's good practive for me speaking Hebrew.

Other than that security in Tel Aviv is less annoying than in most places. They are not obsessed with belts and shoes or fluids. A can of deodorant travelled with me from Tel Aviv via Amsterdam to Dublin and was finally caught half a year later in Hamburg.

One time I arrived in Heathrow from Tel Aviv and was trying to catch my flight to Dublin. I had two hours. I didn't make it. Heathrow security thought that terrorists are most likely to arrive from Tel Aviv and therefor did lots of long security checks on transfers arriving from Tel Aviv continuing to Dublin, i.e. me. I would have thought that any terrorist arriving from Tel Aviv in Heathrow would already have missed his chance!

A few weeks ago security personell in Hamburg, always trying to avoid racial profiling accusations by avoiding Muslims like the pest, picked me for a bag search event. They had me remove every single item from my carry-on and name it. That went well for a while until I opened a small pocket compartment, removed a book from it and said "prayer book". At that point they apparently realised that I might be a Muslim and they immediately ended the search and let me go. (I am not a Muslim and it was a Hebrew prayer book I carry with.)

All-in-all I find those security checks amusing. But I do think that Saudi-Arabia should pay for them.

After all, they paid large amounts of money to the people who made them necessary, and why should they be excused from from fixing what they broke?

They need to look at the passenger manifest and see if there are any Islamic people on board. If theres none... were all safe no matter what we're carrying.

Better google Lockerbee if you are serious

That is EXACTLY why they have to check your shoes - so you don't pay for a survival horror with one life only, but for a safe trip from A to B.