other than the fact that I pay taxes that go to help fund the FAA and you don't.
That's fair. I am not producing any costs there either. I am not calling WX BRIEF or duats to get my weather (I am paying 80 Euro a year for this to the German Weather Service DWD), I am not using any ATC help in the US, but in Europe (and I am paying AvGas taxes making a Gallon 12 USD, no joke), I am not getting any tax advantages in the US (and I am depreciating my Cessna according to the German rules: in 21 years, funny, eh?), so why should I pay taxes for this plane in the US? Because you do while using the system?
And: as I don't produce any costs I am not adding to your bill in any way. Your payments stay the same - if I am on the N-Reg or not. So why do you care?