What are the special situations where 1 gives way to 5? The well-regulated part would imply to me that the possibility of slipping to another situation are eliminated or not allowed.

Blizzard. Heavy rainfall or wind. Sudden crowd / riot / chaotic event.

Pretty sure you can't legislate those out of existence. And sadly I think the fact that these vehicles are being developed and tested in Silicon Valley is either a cause or an symptom of their probably inability to deal with those kinds of conditions.

Erm, china has more than a dozen well funded self driving efforts, some of them by very big companies (baidu). Those are being tested in places like Beijing, you never hear of them because you aren't looking outside of the USA.

I wasn't suggesting legislating the conditions out of existence. I was thinking that kind of situation could be considered in the regulation. Much like VFR flight conditions a self-driving car would not operate in heavy rain/wind or low temperatures.

Also, accidents, road spills, random obstacles, construction, animals.

Road spills, random obstacles and animals all have to be dealt with for any of this to work at all. Construction can be considered in the regulations and self-driving cars can just be restricted from auto-drive mode in construction areas.