[fulafel]

If the citizens don't want it, then of course it's game over.

If the citizens do want it, you can just gradually make private car ownership more expensive and less convenient vs public transit.

Anecdotally many anti-public transit opinions from US folks seem to be around having the less well-to-do present in buses, complaints about hygiene and/or safety. So maybe improve the social safety net at the same time, or go full classist and have separate 1st class & 2nd class compartments.