Oh we did plenty of other things too, acorn was just gravy. We saw the WWII Museum, swamps, and we have friends there.
I may be wrong but aren’t airports partially funded with public funds? I can’t imagine they are fully funded on user frees alone.
Airlines and air freight companies have paid user fees for the construction and maintenance of the the major passenger airports since the early 70s. Those costs are, of course, passed on to passengers and freight customers. Large airports are pretty much self-financing. However, there is a program that provides federal subsidies to airlines for providing service to some small airports, depending on how effective their legislators are in getting them the funding, which is delivered in the form of grants. All that said, there is a difference between an airport, and an an entire system of passenger train service. A better comparison would be between airports and train stations.