My experience comparing rules in clubs and FBOs doesn't match yours. But
perhaps I'm misinterpreting what you mean.

You are.

FBOs are far more strict about utilization rules (which can be expressed as
additional fees like daily minimums) than any club I've seen, for example.

That's exactly what I don't mean. Those are fees, not rules. They
don't tell you what you can and can't do - they merely impose a
strictly financial cost. They don't tell you that you can't make a
particular flight - they merely tell you how many dollars you will pay.
Nothing else.

The one possible exception is that we've currency rules on our complex
aircraft that are more strict than those on any of the other aircraft.

Now we're getting somewhere. Yes, that's the sort of thing I'm talking
about. Some other club examples (all real):
Maximum crosswind limit 10 kts - google for this one, it was discussed
here.
No formation flying in club airplanes.
No aerobatics in club planes. Even the aerobatic ones. Not unless the
designated aerobatic instructor approves. And there is no designated
aerobatic instructor, and hasn't been in years.
No night flying without an instrument rating. No flights more than 200
miles from home without an instrument rating.
You get the idea. It's not that FBO's don't ever have such rules -
some do - but it's a lot cheaper (and often politically easier) to be
checked out at several FBO's and just choose the ones with rules that
work for your flight than it is to be a member of several clubs.

But these are just the explicit rules. Clubs can also have safety
committees - ones that can decide to ground you, make you fly with an
instructor, whatever - because they decided you weren't safe. Of
course an FBO can also tell you that you're not welcome to rent there
anymore - but you have little or nothing invested in the FBO. Also,
the FBO has to make that decision carefully - it affects his
pocketbook. Not so the club safety committee.

Paul made a statement - that the rules will only be enforced against
you in the worst possible way if you're a complete dick. Just remember
- YOU don't get to decide if you're a complete dick. Someone else
does. Someone who may not like you.

Michael