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.
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.
You can replace the buffer stop with an incline too steep to climb with the available traction at which point their best bet is derailment by going too fast around a turn. But again, with properly banked curves the trains simply can’t go fast enough for that to happen.
> You can replace the buffer stop with an incline too steep to climb
There generally isn't the room to plop down hills instead of buffer stops. Instead it's possible to use energy-absorbing buffer stops (rather than the traditional "hard" buffer stops), possibly with e.g. dowty retarders on the track beforehand to force specific speed ranges on incoming trains.
If a train hit the end of the line at London Paddington at full speed it would be absolute carnage, surely. Not a guided missile with freedom of movement, but it's already heading in the right direction.
Even if you were going fast enough, you couldn't take one and crash it anywhere you like.
Into the platform at Grand Central, maybe. Into the WTC and Pentagon, not so much.
Some kind of automatically enforced speed limiter when the train detects that it's near the end of the line would probably not be hard to implement, or maybe has been already. IIRC many trains automatically slow for curvy areas of track.
> Also aircraft security was too much even pre-9/11.
In 1998 I was able to walk onto a plane in Sydney and fly to Zurich and walk off while barely breaking stride (I only had carry-on luggage, and Swiss customs waved me through based on my passport being US).
Trains have automatic systems that engage the emergency brake if they ignore stops or go faster than allowed. They are not completely foolproof, but it's pretty hard to crash trains.
