When can we have an intelligent discussion about what licenses for self driving cars would look like?

We license drivers now. It seems clear that software should have to pass at least the same bar.

Unfortunately everytime it is raised it ends up being a discussion on the effectiveness (or lack thereof) of regulation.

My view is that Google's version of a self driving car may be perfect, but I'm unconvinced that "vendor modifications" (to steal a term from the Android world) will always be as well-coded.

What would an appropriate regulation/certification/licensing regime look like? How are updates handled? Are users allowed to modify the software themselves (with or without re-certifying?)