I think it's more that there is a big dangerous gap between semi-autonomous vehicles and fully self-driving cars, and car companies are trying to figure out where to draw the line. Tesla, I think, takes too many chances, and GM probably is erring so far on the side of caution that most people won't use it.

Personally, I don't really have any use for a self driving car that makes me pay attention to the road. The primary 'cost' of driving isn't that i have to move the steering wheel a bit, it's that I can't do something else when i'm driving.