I think this indicates where level 3 is a slippery concept: it looks like it could be useful in this case, if you think only of the times when it works properly, but the only reason for a system to be level 3 is that it cannot qualify for level 4, meaning explicitly that it cannot be considered safe enough without having an alert human to fall back on.

I took a look through the level descriptions for a level where the human is driving but is being monitored by the system, but they all seem to be versions of having the system drive while being monitored by a human. Maybe we can do more in the way of collision avoidance as the technology progresses towards true autonomy.