I was a pretty crap driver before I was 23 (regardless of what I would have said then), but I'm not too bad now. Although, it depends on what you measure, I suppose; I've driven behind a Waymo vehicle, and they stay in the lines a lot more than me (which could be a positive for following rules, or a negative for increased drive times), but I also didn't ever change lanes into a bus expecting it would move, and I can avoid some of the annoying driving behaviors I used to see with Waymo (signal a lane change, decide not to do it, loop); not sure where they're at with that since I no longer live in their test areas.