I still think that's an issue between an employee and the person who hires/pays them. Yes, it's my money that keeps them in business, but I'm not in charge of the agreement they have with the person who hires them as to what they will do all day.
My boss pays me according to what he sees fit to pay considering my work. If I'm not worth what he's willing to pay, things change. But that's between me and my boss - not a 3rd person.
I used to work in a retail shop (summer in-between college semesters) that had quite a bit of downtime. It was a specialty shop. And when there weren't customers in there, I did all I could do - I made sure the store was clean, I rearranged merchandise to get some of the stuff in the back up front, so it got noticed and possibly bought, I made sure the storeroom was clean. I did everything I could think of to do. But, even with all of that (and even as the only employee in the store), there ended up being a lot of downtime. So I read. I tried to read some of the books we had on the subject relating to the store (so I could be knowledgeable about our product and things like that). But, when all else failed, I read my own books. And put them aside the second a potential customer came in. My boss - the owner of the shop - deemed it worthwhile to have me there despite the fact that there was downtime in which I didn't have anything to do in the shop. It allowed her to leave and do things for herself. In fact, I was given a key to the place, and there were weeks where I wouldn't see her at all; I was, seriously, the only person running the shop. It was no one else's business what she paid me or if I had enough to do; it was solely hers and my business alone. Even if the customers' money was financing my paycheck.