The woodshop I worked at as a teenager, wasn't big on safety. We never did, UNTIL a retired Square-D engineer we were working for came in one day.
He saw one of the guys putting on a dado set without unplugging the saw. He had a hissy fit. Our saws had Square-D switches. He told us that saw dust gets in that old type switch and could turn the saw on by itself for no reason.
After that day, we never put our hands,etc. near the sawblade without unplugging the saw.
About a year later, I dropped a small piece of wood on the top of one of the saws, and the saw came on. Luckly, the board wasn't near the blade. Took the cover off the switch, and blew the dust out.