Jose wrote:
Often club membership has a waiting period, based on the number of
airplanes and on the number of instructors. As a result, instructors
usually do not have to wait to join and they may even get a discount
on fees ad dues.

I don't think the waiting period waiver would come into play, but the
discount on fees and dues just might, depending on the FSDO. I'd find
it a very weak argument however. It doesn't make the CFI an employee,
nor does it have the CFI "supplying" the aircraft.

Sort of the gold standard is where does the money go. If I pay the
"club" for the instruction and they pay the instructor (most likely
keeping a "cut" for themselves), then it's pretty clear. If
I go out and have to deal with the paying the instructor (even if
he has to be vetted by the club and/or their insurance provider)
then you could argue that the 100 hours aren't required.