Aye, but sometimes the rabbit must die! AP1 had no rain sensing, so he is beyond parity with the ME system. And current cars could have identical performance, if they had the same sensor. So one could criticize the design decision to no remove it so soon, but one should not bestow upon AP1 features it did not have.
It was not so much an attempt to bestow the feature on AP1 than to shed light on the limits of even Karpathy’s prowess: speed-sign recognition and reliable rain sensing are still missing.
I think they do it for themselves. Back when I coded HTML and I was dealing with div's I would place an outline of one pixel in various colors to move things around the page as I needed, sometimes I needed to see how theboxegs were overlapping each other because I didn't use the right attributes etc. Putting the outlines on made it easier for me to see what it was doing. Human eyes need to check how its working, so they can check the accuracy of the IA with their own eyes by reviewing the footage, I would have totally used colors and put outlines on it to "see" what the heck it was doing. Easy enough to turn that stuff on or off.
My understanding is in some of those cars there are humans in them able to over-ride at any given time.