PFCs are certainly taxes, but let's clarify that the money stays with the local agency/authority (and according to the FAA may only be used for certain improvements). See http://www.faa.gov/airports/pfc/ Granted, money is fungible so this isn't always as clear cut as it could be. However, this doesn't affect the federal general fund, at least not in a meaningful way.

We can argue the costs/benefits of such user taxes, but ad hominem attacks don't advance the conversation. If we're going to debate this, let's at least stick to facts.