I stayed at a very basic one (no showers, outside loo, outside sink for washing dishes, did have EHU) when going to the NEC MH Show last month.I have found that the basic ones I stay at, probably 10% ask if I am a member and look at my membership card. I think most are just happy to get your fee for the night.
Not sure about the posh/expensive ones though...
K
We're in both but do prefer to wild camp.
For us, it is not about saving money.
We're just anti-social beggars, and prefer the solitude of a remote park up.
Many of the National Forest sites have no-overnight parking signs. If they had a membership scheme where one could pay an annual fee and get an overnight parking permit that would suit us to a tee.
Sorry, wandered slightly off topic there. In light of the above, I meant to say "therefore we prefer the small site's network"