[ghaff]

I'm inclined that improving systems up to full autonomy for many highways in many weather conditions is a fairly realistic maybe 5-10 year plan. Which would actually be pretty nice and potentially a big win for safety.

The problem with widespread L4/5 is that you need to get to a car that can literally drive itself between 2 points on a map with a high degree of reliability, in a wide range of weather conditions, on roads of varying conditions, with unexpected/unmapped obstacles that may require doing something technically illegal to get around, without human help. And that, as you say, seems really hard.