Played with two guys (who were pals) in an open comp.
One of them air mails a green and ball goes into trees behind the green. We have a search and find it, unplayable, so guy decides to take a drop. I'm not marking his card so I wander off to let them get on with it. Look back and he's dropping in the open space between the green and trees (i.e. in a nice spot about ten yards nearer the hole). I had to go up and explain why he couldn't drop there and what his options were. Couldn't tell whether they were "at it" or just didn't know the rule.
Its amazing how many [golfers] who have been playing for decades think they can drop in a spot with no obstruction rather than at the NPR! If the NPR is still behind a tree, tough!
And don’t get me on ‘activity’ because there’s some animal droppings near the tree he’s tucked right up to and is looking for relief, if the balls not in a scrape or your stance isn’t affected by a burrowing animal hole, tough!