You have different companies responsible for operating the train, the tracks and providing services inside the train. Planes are similar but international services are common and better organized.

I’m not sure what you are trying to say here, because you imply that this isn’t an issue inherent to trains since the solution in the aviation world is to contract ground crew where airlines have none of their own, which could very well be done by train operators as well.

Also, being stuck inside an airliner while taxiing, with no A/C, just because the systems malfunction slightly and tower don’t agree on which gate they could assign to the flight since it is very early, is a thing I’ve gone through a few times. So, again, not exclusive to trains.