Sounds like you and OP need new jobs then. You don't need to allow yourself to be used that way.

Or if there are cameras and higher management just report them. Many people may be skeptical to report their manager to a high up but really if they aren't doing their job its often appreciated by the higher ups.

The conundrum of managers to employees...

That, or the Co-Worker was actually being taught how to clean the gum up from under the tables.

If they're anything like my old job they'll make up the excuse that the cameras don't catch that area when it clearly does or that the camera is just there for show..

I'm wondering where OP works, is this a walmart or is this a restaurant? Cause the restaurant image is a whole lot funnier in my head. "Sorry you can't be seated at that table, my manager and coworker are currently busy hiding under it"