Happen in 1999 at the plant I was at, cleaning guy lost his hand.
Maintenance member tagged/locked the machine and midway through went to lunch. Sanitation member came back, added his lock and went to work cleaning out the auger on a 10,000 lb grinder. Maintenance guy comes back, removes both locks and without checking the machine, powers it up.
Imagine leaving a lb of hamburger on the kitchen table for three days during the summer. The meat turns black, all the fliuds settle on the bottom and leak away from the meat. The stench it creates, can be smelled out the front door when it's opened, even by the neighbors.
Imagine one more thing, it's actually a person and you have to put them in a body bag.