Yesterday my self-propelled lawn mower stopped propelling. I shut it off, turned it on its side and the belt was okay but would not turn and the pulley from the motor was okay. I had to take off the plastic cover over the belt on the deck only to discover these screws holding down the cover on the pulley. I have something to remove about every screwy screw but not these square ones. The top of the screws is rounded so you can't get it out with vice grips. Had to grind down an Allen wrench to the right size. A small stick was jammed between the pulley belt. The belt was okay but 4 years old so I decided to replace it and got one at HD for $15.
I later called a local dealer and asked what it cost to replace the belt. Seventy-five dollars for labor plus the price of the belt - $23.
So, that's why the do it - to drive repair business to their dealers. Outrageous!