A lot of bus routes suck and people don't like to plan ahead for how they'll get someplace, so they often default to the most general transportation available (personal vehicles) if the transit network isn't good enough for everyday tasks.
As an example, my wife's 15m car commute would take 45m by bus transfer to the nearest stop, which is a couple miles from the destination on a freeway onramp. The transit system is fixing it, but that date is 3 years away. That's still better than the routes some people have.
And lest you think the local transit agency sucks (by American standards), they don't. They just prioritize office workers heading to/from downtown instead of people moving radially through the metro area.
I know a lot of people who live by like 10 min frequency routes or better and usually its me revealing their existence to them when I use it to show up to their house. Could it work for all trips? Of course not. But plenty could be done on busses as it is. People are blind to them though. No one bothers to look at transit system maps. They see the couple rail lines listed on google maps and assume there is no other transit offering.
I had to carry a couple of gallons of dairy for a trade show. Too heavy for the 15 minute walk. First world problem, I suppose, but Waymo was a convenient point-to-piont option.
