Considering that dump stations are disappearing at such an alarming rate, I don't feel it is entirely unreasonable to pay some sort of fee to dump. The "bait and switch" that the OP experienced was probably just an omission on the part of whomever he was speaking with.
From time to time, I've asked why someone closed up their dump station and the usual answer is that people were mistreating the privilege and it just wasn't worth the hassle. I never got the impression that a dump station was a major profit center for a business.
Last weekend I was at a truck stop that had one of those automatic dump stations where you feed in a $5 and the hatch unlocks. I think they call it the SaniStar or whatever, but anyway, the sign said that the dump station was permanently closed. I asked why. I was told that people were too cheap to pay the $5 to open the hatch so they were just dumping their tanks alongside the hole and it was becoming too much of a hassle for them to deal with.
It is behavior like this that is costs us all.