If you mounted a forward-facing video camera on every car in in the world and gathered the data for decades, you'd still be nowhere: you're missing the side and rear views. This is a thought exercise, but it demonstrates the point. If your robot car has a blind spot, all the data in the world won't fix it.

Nobody knows how good these cameras are, but every camera-based system so far has had the same critical limitations: they don't work well at night or in poor visibility.