A lot of the players in this business hate that idea (a bunch are avoiding that kind of system) because people are godawful backups. They’re prone to dozing off, zoning out, goofing around. But if you want an autonomous car that can roam beyond a constrained geographical zone, or that can stay on the road in less than ideal weather conditions—and you want it this decade—you’re gonna need some human help.
As long as you need the human help they're neat, not revolutionary, and certainly not meaningfully safety-enhancing in a way that people will tolerate.
This will be useless except for niche applications.
Ford, though, is aiming to launch its first self-driving car with level four autonomy. This means its vehicles won't have a brake pedal, accelerator, or steering wheel and will be able to operate in a predetermined geographical area without human intervention.