It's also easier to stop a train, get off a train, or prevent collateral damage in case of malice/accident. Survivors are also a lot more likely if there is an accident, mostly because of gravity.

Very true. Even in the worst train derailments you never hear that there were no survivors.

Assuming passenger trains of course. I think a freight hijacking is far more likely. The danger posed by a hijacked freight are evident from the huge numbers of lives lost from exploding petroleum trains over the past few decades.

TSA isn't really for hijack protection, that was solved quite quickly after 9/11 with effectively impenetrable cockpits.

It's really for preventing destruction of the plane itself. A large bomb on a train underground could cause way casualties, which is why the strictness of the TSA is puzzling.

If it really puzzles you then read a little bit on Michael Chertoff and immediately all pieces of the puzzle will click.

Hint: its all about money.

https://en.wikipedia.org/wiki/Michael_Chertoff

Google is your friend but this is good piece:

http://www.washingtonpost.com/wp-dyn/content/article/2009/12...