The fewer people that drive, the less you have to expend on massive road projects and the better the experience for anyone who actually needs to drive. The whole bicycle infrastructure of a city like Amsterdam probably costs less than any single major highway, and the number of cars it eliminates from the road is massive. In my experience though, once a place has become car dependent, the attitude changes into one where alternative city design is almost impossible to contemplate. The assumption just becomes that adding a lane to a highway is the best course of action even though it doesn't really increase the flow that much at all.