Public transportation needs to be a public cost, paid for and funded by tax payers and not for profit. When transportation is subsidized but privately owned, then you will see maintenance neglected in an effort to raise shareholder value.
There is no public transit system where fares cover all the costs, never mind generating a profit. Riders would refuse to pay a fare high enough to do this.
Airlines barely make a profit. I'm not sure about intercity rail globally but in the USA, Amtrak relies on government subsidies to operate. All the private railroads gave up passenger service decades ago because it was unprofitable in the face of new competition (i.e. cars and air).
Local bus and light rail service will never be profitable as a private enterprise. We'll see what happens once drivers can be eliminated, but I'm still doubtful. Plus the public will still want some sort of authority figure on the bus or train. It's one thing to feel safe in a Waymo where you're not sharing the vehicle with 20 strangers but a bus or subway is different. So trade driver for security/customer service person and you're not really saving on payroll.