Avis isn't alone in this. Some of the fees are by the rental agency, others are "taxes" imposed on out-of-towners by locals since the travelers don't vote locally.

If you're renting for more than a few days, your best bet is to take a taxi/train/bus/other to a non-airport location and rent from there. You can avoid nearly all of the crappy fees. The risk is that the off-site location won't have much of a selection, but you can always get the vehicle there and then swap at an airport location during your rental sometime.