Since you didn't specify golf courses alone, I would add buying a new $500 driver every year or $45 dozen golf balls every week as the biggest individual waste.
For most golf courses, another waste is probably the 7000+ yard tees, which only are used by 1% of players, if that. Now, if they are sized to a minimum 15 x 15 feet, and the first 180 yards or so to the fw is lightly maintained, then they probably aren't too bad.