If there is a charge for a specific service, and that service is not
used, you will not be subject to the charge.

However, since GA is in reality a heavy user of FAA capital
infrastructure...

First, I asked about your =reasoning=, not about the premises
themselves. You responded with the premises. First, to deal with that:

The flaw is:
1: the use that GA makes of some of the services is because they are
mandated, not because they are needed.
2: the infrastructure does not really benefit the GA aircraft that are
using it - at least not to the extent that it benefits other parties.

Consider Bogus Internal Airport (BIA). It's a small field, GA has been
using it for years with no tower, and no real services. So, I should
not pay (much) in user fees to land my Archer there. However,
Humongougs Airlines Incorporated decides that it would make the perfect
gateway to Lesser Paradise, a little island that is growing in
popularity. To do so, the runway is lengthened and a tower is added.
None of this benefits me. Now the airspace is class D and communication
is required. I have to buy a radio with my own money, but the reason is
to accomodate Humongous Airlines, not to accomodate me. Every time I
take off, I would pay a user fee for this new long concrete runway and
the spanking new tower, and the fees for transmitting on the radio, and
I'd use more gas because my flight path has changed to keep me out of
the way of the approaching jets which don't interest me in the
slightest, except that I would be a bug splat on their windshield.

I fly out of there and do touch and goes. They have five flights a day
and are in discussions with three another airline for connecting flights.

I'm a "heavy user" of this infrastructure because I use the concrete and
the tower and the radio EVERY TIME I go around the pattern, but I'm not
really a beneficiary of it. It wasn't put there for me. The airlines
are benefitting from the infrastructure, and from the procedures
designed to keep me away from their windshield. Now, while I also
benefit by not becoming a bug splat, that benefit is more like the
benefit of stopping hitting my head with a hammer.

Granted, the airport is ficticious, but the principle is valid.

Now, on to my original question, which related to your =reasoning=, not
the truth (or falsity) of the premises.

You posted words to the effect that iit is disengenuous to think that both
(1) GA uses few services...
and
(2) user fees would be prohibitively expensive.
could be true at the same time.

They can certainly both be true at the same time, depending on how "uses
services" is defined, and how user fees are allocated.

It is disingenuous to think that, given the political clout of GA vs the
airlines, these definitions would not be skewed in their favor, in the
same way that flying was restored to the harmless airliners shortly
after 9-11 while spam cans were still banned from the skys (and are even
today virtually banished from the capitol, where, granted, there is so
much hot air you don't really need an airplane to fly!)

Jose
--
You can choose whom to befriend, but you cannot choose whom to love.
for Email, make the obvious change in the address.