I believe they are a 'tax' invented my Hotel Owners to juice their revenue and be able to publish more attractive initial rates...scam tax IMHO.

The next time the 'Destination Fee' rears it's head make sure the ask the FD to explain it in detail and whether it is in fact a government imposed tax and if not, what are you getting for the 'fee'. It's not going to change things, but you might be savagely amused by some of the answers/explanations you get.