Private autonomous transportation will allow that public infrastructure to be tenfold more productive.
Public transportation will never have the incentive to minimize cost and headcount.
Where we do have public transportation, it should always face competition from private offerings - including on the tracks, as they do in Italy, for example.
Of course it has the incentive. Even in this thread people are getting mad about it costing too much.
That's not true. For example, France is rapidly automating its metros. The US is quite unique in viewing public transport as a jobs program rather than a public service.