I think that's a bit overly cynical. Most people that support public transport support the 'idea' of public transportation (I don't) and mass transit generally (I do). They do not support it on the basis that they'll have a clear road to drive their own cars; a few may, but most aren't even thinking of their next trip anywhere.
However once you need to go somewhere, the more immediate practical effects take over: reckoning with the inconvenience, inefficiency, and terrible service offered by most public transit organizations becomes the present concern and you take the best, fastest, and most efficient path for themselves in that moment.
I've seen a couple notes about the San Francisco Bay Area's BART. I actually take BART and might more often if it were closer. While I don't agree with how they exist, that they do and do a reasonable job makes them viable for me. Now there is a light rail/trolley thing run by San Francisco that stops directly outside my house. I won't take it. The service sucks. It's not worth it even compared to the horrible traffic in SF. If I have to take MUNI, I will walk a mile to BART, drive, or just not go.
However once you need to go somewhere, the more immediate practical effects take over: reckoning with the inconvenience, inefficiency, and terrible service offered by most public transit organizations becomes the present concern and you take the best, fastest, and most efficient path for themselves in that moment.
I've seen a couple notes about the San Francisco Bay Area's BART. I actually take BART and might more often if it were closer. While I don't agree with how they exist, that they do and do a reasonable job makes them viable for me. Now there is a light rail/trolley thing run by San Francisco that stops directly outside my house. I won't take it. The service sucks. It's not worth it even compared to the horrible traffic in SF. If I have to take MUNI, I will walk a mile to BART, drive, or just not go.