Camp ground tried to charge me for there heat tape

It's hard for me to see how RV parks can be required to "only charge what they pay for electricity"- wouldn't that mean they'd have to constantly adjust rates that include it?

It may be that if metered, they can't add an upcharge beyond the rate they're paying, but there's no indication here that's the O.P.'s complaint, which seems mostly to be that he's paying to keep the water pipes serving his site thawed. I just don't get the logic that says a user shouldn't pay for that!