A robo-taxi is private, arrives when you call it, and goes directly from where you are to where you want to be. I don’t see the similarities between that and bus.

A good public transit system leaves from within 5 minutes of where you live and goes to within 5 minutes of where you want to be in any town of more than like 40k people.

A good public transit system is also better for the environment, makes traffic less awful, and is generally just preferable to robotaxi bs.