Completely agree with the ball mark repair being ignored, but my top is certainly SLOW PLAY! blatant behaviors as mentioned here, pre-shot routine, over analyzing putts, etc etc
I think there are a lot of people who in the name of fast play don't bother fixing their ball marks or filling or fixing divots.
Accordingly, I am not a fan of courses who do not have divot mix/sand in carts or available for walkers. Even up here in New England, I would say roughly 50% of my divots are either too small to pick up and replace all the pieces or disintegrate. Likewise some public courses don't have them on tee boxes. The last time I played, when I hurt my hand, there were no divot mixes on any par 4 or 5 (even ones where it was obvious most people were hitting irons) and maybe 2/3 of the par 3's.