Other countries provide transit as a transportation service for all. US politicians and voters view it as a charity for the temporarily carless.
All the other issues are downstream of this mindset.
Perception, maybe? My local transit agency seems to do pretty well. There will always be critics, but they don't seem unnecessarily bloated, the vehicles are well maintained and clean, etc. Not any different than a typical bus in, for example, UK. And I would caution that if you think everybody other than the US does government-owned transit very well, you may be focusing in a small subset of wealthy first world countries.
I'm guessing that unlike here, some of those places need buses, and they simply can't afford any waste.