I always interpreted the comments to limit the ability to call a let for balls on your side of the court. Not saying that I'm right. The alternate reading is that you can't call a let for the court next to you when your ball intrudes onto their court. Any super rules gurus out there care to clear this up?
USTA Comment 23.4: Who may call a let? Only an official or player may call a let. A player may call a let only on the player’s court.