Earlier quoted context omitted.
The security won't get blown out of proportion for trains like air, because while trains can do significant damage to themselves and surrounding buildings - you cant take one and crash it anywhere you like. 9/11 never would have happened with a train. A hijacked plane is a missile.
Trains still have an "end of the line." So, yes, you could if you were going fast enough. Also aircraft security was too much even pre-9/11.
You can overrun the buffer stop (happened last year at O'Hare, a blue line train overran its buffer stop and climbed up an elevator) but you're just going to go a bit past the buffer stop (relatively, most likely a fraction of the train length), at best you'll get just outside the station Montparnasse-style (https://en.wikipedia.org/wiki/Montparnasse_derailment). That's hardly a guided missile with complete freedom of movement in the same way a plane is.
You can't drive a train into the white house no matter how often you try, because there's no rail leading to it, or even ending in its general direction, which is anywhere near enough the white house for that to be a concern.