Well, if you look at the grant money, and where it comes from (not just ticket taxes but also GA fuel taxes), and where it goes (mostly to large airports)...
I imagine that if you tracked the income and outgo of the trust fund, and broke it down between money coming from ticket taxes and money coming from fuel taxes, and money being spent on air carrier infrastructure and money spent on ga infrastructure.... You'd find the the GA might receive more than collected. But I'm not sure how much more. And remember that Stafford was built to be a reliever airport, to reduce congestion at air carrier airports.
Every major infrastructure investment (airport, rail station, power plant, dock) is underutilized in the beginning in a well-thought-out system. Dulles was criticized as a huge waste of money, as was Denver, as was O'Hare. See my earlier post for motives for this type of reporting.
As for the property taxes, that's up to the local governments. Many of them feel that they are doing the best they can with their taxing choices.