Although most of what you said is true I think it is dangerous to assume that a license will be revoked if I stop paying a central agency. They can change their mind (if the federal aviation regulations give them ground to...i.e. failing to meet medical requirements, criminal activity, non-compliance with regulations, etc.) but we don't have to pay the FAA a fee to keep our private pilot license/certificate. Our licenses do not expire we just have to renew our medical certificates and complete a biennial flight review. All we do is pay for the testing (and the schooling) and pay whoever for our biennial flight review. However, I'm sure if I stopped paying my taxes they could muster up some way to, not only garnish my wages, but revoke my flying privileges as well.