It is not so much about being "public utility", it is about competition, if you can't have competition there is no point giving the rights to some private compa

It is not so much about being "public utility", it is about competition, if you can't have competition there is no point giving the rights to some private company which acts like a monopoly. Transportation is also public utility and yet it makes sense to have different taxi companies or airlines. The interesting question is when you got something that you can't compete with directly like a train line but can compete using other methods like buses or airlines. In that case there might be more incentive to a train line operator to give a good service because of the competition.