"They would not be there if they weren't getting paid for it."

That's not true. There are nice people in the world.

I know what volunteering is: I do it myself. Every week I spend several hours helping kids with their homework at a local school. This is not at all the same thing as spending 8 hours a day working a cash register, dealing with rude customers without being rude in return, being expected to cover coworkers' shifts when they're sick, working during holiday hours instead of spending time with family, etc. etc. etc.

Your response seems irrelevant to mine.

Being nice is not a behavior that is only exibited when paid to do so, as you seem to believe.