I think the comparison to google translate is interesting. How much confidence do you have that a translation by google translate is correct? How would you compare the complexity of translating documents between various languages to the complexity of driving a car in arbitrary environments and situations. And the most interesting think: Would you trust your life on google translate? At least in the sense that it does not corrupt the meaning of a translated text (small errors ok)?
The way I see it panning out is that the first generation of autonomous vehicles is going to have a tough time. As more and more cars become fully autonomous there will develop some sort of protocol where every autonomous vehicle will be relaying exactly what it's "about to do" to anything nearby. I.e. your car will know if the car in front / behind / on the other side of the freeway is about to do anything and thus eliminate what is currently seen as "unpredictable environmental factors" to a very large extent. Internet of Things will also increase the amount of additional data being fed to the car's computer, e.g. it will know exactly when a traffic light is about to turn red because they will receive this data directly from it.
Once you reach a certain critical percentage of fully autonomous vehicles regulation will probably change to such an extent that car insurers will void your insurance if you drive it manually, or give a significant discount to your insurance premium if you don't ever put it in "manual" mode, etc.
I think the problem is really difficult right now because humans are still allowed to drive, but as that ratio goes down it becomes less of a serious problem.
