I don't know if it is a US problem. More of a sunbelt problem. There are many cities in America with reliable mass transit. And Pleak, rail is definitely more attractive to potential transit users than buses. That's not even a debate.
If I'm correct, I believe their beef is also that Southwest wants international flights at Hobby instead of IAH. Not saying they'd be okay with them if it was at IAH instead, but I think that's the crux of their dissatisfaction.