<font color="blue"> (since they get paid at least .05 cents a gallon for waste oil, it was real nice of them to allow you.) </font>
A guy I know runs a self service boat yard. The yard provides a waste oil tank for the convenience of its customers. They do sell the waste oil, but the company that buys it dings them hard if some jerk dumps antifreeze or any other form or contaminant in there.
Since they can't watch everyone all the time, they frequently get dinged. If they had a real choice, they would get out of the waste oil business, but they can't because their customers depend on that tank being there.
My point -- Just because a business takes waste oil doesn't always mean they are making money from it. There are expenses involved, and it may even run at a loss. Some states require stores that sell oil to collect old oil. They have no choice.