Chicken and egg problem. If you start with the assumption that you have a car, they are pretty great. Quiet, no through traffic and can become neighbourly, potentially large blocks. Somewhere to park your car...

Basically trying to retrofit busses to a development built around cars is stupid.

Sadly yes. Normally it isn't a cul-de-sac. It is a neighborhood with several streets, but the streets are more like a maze so that residents can get in (they know the way), but anyone just passing through cannot find a path (without a map). Since everybody has a car it is only a couple minutes to a main road and so good enough - but that is still a long walk and so nobody walks to get places. (People do walk their dogs on the sidewalk, and generally there is a park inside that the kids will walk to)

It isn't big auto that designs these places. Big auto likes them, but the people like it because they don't know anything other than cars, and they know they hate living on a busy street with lots of cars. Those are the only two options they know about so don't bother replying with all the others you know about, they don't exist as options.