You don't think that people who use services care more about the service than non-users? Whether they're forced into using it or not, the fact they do absolutely makes them more invested in it being good.

Civic and national pride makes citizens (which includes politicians and the wealthy) more likely to care about the actual state of their country. That's what national pride means, as opposed to nationalism, where they are proud without reason. Is public transit guaranteed to be one of those reasons they feel pride or shame? Not at all, but support for it is certainly more likely to come from that than a bunch of nationalists who don't actually feel any shame at failings of the country, of which public transit is currently.