Public transit works perfectly fine in a low-density situation. Your urban planning needs to accommodate it, though, with walkability being a prime concern.

A car-centric city will never mesh well with public transit no matter how dense it is. The best you can hope for is good subway coverage but that’s expensive and can’t be done everywhere. Nobody wants to take the bus if they feel they have no safe route to the bus stop.

But if everything is opened up with proper sidewalks and bike lanes and maybe tram tracks, if street lights prioritize pedestrians over cars, if walking to the nearest convenient stop feels safe and effortless even if it’s two miles away – then you get public transit that actually works.

It’s not terribly difficult. But your urban planning can’t be car-centric or you’re getting nowhere.