Why cant the train and infrastructure be run by the state- while the service inside is run by a private company?

Like, the company rents the traincar barebone and puts in seats, foodstalls, wifi, ac, etc.

Finally, while we are at modernizing, can we get maglev trains - with detaching and attaching passenger cabins? Because, the real slowdown in europe is local "little" emperors having a say where the train stops, and theire voters region is that one place, the ICE has to stop.