£11 per night to take my wife. wow

I too would suggest to the OP that he and his wife try a few CLs, for which of course he needs to be a member, most are reasonably priced and some are a positive bargain.

 This year we have used one in Wales that has serviced hardstandings, and a toilet and shower available, all for £18, and one near York where a huge serviced hardstanding was £22, for all of us (3 adults and 2 children), but no toilet or shower available.

However, to expect to get a full facility site for £23 per night for 2 adults is pretty much unrealistic in UK in 2024.  Last year we used a full facility small commercial near York where a serviced hardstanding was £28 for the 2 of us,  this year it is now £34.  It was, and still is, however less expensive than the comparable Beechwood Grange CAMC site.

Not to at least use his membership to try CLs, would be a shame, and  could also be called “a waste of his membership”

When we were touring abroad, few years ago, using camp sites not Aires the pricing structure was often price for pitch, price for unit and price person. Is that still common?

AcsiCamping Card gives an inclusive package price for two adults, car, caravan or motorhome, awning, EHU, awning and dog. 

And with automated entry and exit at CampingCar Parking sites there is no one there to count the number of people in the vehicle.

I think it was common in France for campsites to have menu pricing but ACSI, as mentioned by ET, changed that a bit. I suspect sites still have menu pricing for those that turn up without the ACSI card. 

David