I've lived in Atlanta and Seattle. Both have perfectly workable transit. Even if Atlanta does seem to have gotten a bit worse over the years.
Seattle LRT has about the same usage as some german systems trams that are like 20x smaller. For a whole lot of the population that life around Atlanta and Seattle the public transport isn't workable.
Workable is not a great endorsement. If things are not fast and frequent people will prefer to drive even if transit could work. Also both have workable transit only for some destinations - I don't live in either city, but I'd guess without looking getting downtown is easy but if your destination is one suburb over it is technically possible but you could baby crawl faster.