[gok]

They're designed to be survivable for the humans on the trains cars, as opposed to the cars themselves :)

[mcv]

Exactly. Nobody cares about the cars, it's about the contents. And a train that cannot deform, will come to a very sudden stop when it hits an unmovable object, which is not going to be good to the occupants. Crumple zones are generally better.

Downside is that that's probably where the train driver is. Preventing collisions is definitely the better approach.

[kpil]

The procedure is to slam the emergency brake, then run as hell, as far back as you can get.