I wouldn't put much stock in the fact that the sign looked official. It wouldn't take much for a manager to walk next store to Staples and have them make up a sign that looks like any other sign in the store. For all we know, the stores all have the ability to create/obtain signs using the logo and colors. Special sales of excess inventory, local sales ("Riverview High Class of 2019 - Take 10% off this week"), etc.
I'm not saying that corporate isn't aware of the situation, just that the sign you saw shouldn't be assumed to be prove.
It's all relative. DAGS for miter saw accidents. From minor nicks to entire hands having been cut off. Wet wood can kick back and I'm sure you've seen PT at the home center that was literally dripping wet.
Heck, table saw blades don't move in any kind of arc and yet many people have reached into the spinning blade. Mistakes happen. Ignorance happens too. I've seen people using hand saws at the trim aisle cart who had no clue how to support the wood. I wouldn't let them anywhere near one of my power tools.
I'm really surprised that the store is doing that. Do they let you climb the stair ladders or use the fork lifts too? ;-)