Train crashes are still a big deal, but if you're in a train crash and survive then rescue vehicles/personnel will show up. If your plane breaks up or whatever and you survive, you're almost certainly going to die when you hit the ground. Gravity and velocity are much bigger factors than for trains, in general.
The Asiana plane crash at SFO last year where only 2 or 3 people died as the plane crashed and broke up upon landing is very, very unusual.