Without wanting to get into the middle of a 'bun fight' maybe a bit of understanding from all sides could be the answer.
Bank Holidays are reknowned in England for being either excellent or 'Hell on earth' although that is usually the trip home. But as everyone is agreed the sites are usually chokka then possibly extra care and attention is required from everyone. The facilities are going to get a lot of extra abuse and adults as well as children seem to often forget that others would like to use the facilities as well. Without being sexist my wife advises me that the female facilities seem to get a worse hammering than the Gents. Whether this is due to more mothers taking toddlers, or what I cannot comment but she has returned a few times commenting that the state the showers had been left in, left a lot to be desired, and that it was often adults who were the culprits. Even in non camping life we have both noticed that there is an increasing trend for parents with small children to wish to explain everything in great detail, when often a simple 'No' would suffice. We see, and certainly hear them on the buses here in Edinburgh where everything little darling wants to do requires a long explanation. The child also talks incessantly and one wonders how it will survive at school. You do sometimes want to lean over and just tell the mother and child to just 'shut up' but of course you don't.
However, back to sites. As we all know some people seem to think the wardens are there to clean up after them and one does wonder how these people manage at home. Again, for no other reason than personal experience it seems that CC sites are more prone to this problem than C&CC. This does seem curious as the C&CC sites have tenters where they have no choice but to use the site facilities whereas the CC is solely caravans or motorhomes with often luxury washrooms. There also does appear to be trends where regular campers are more considerate, while those who only camp on major holidays are less so. I am sure others will disagree, but again can only state from personal experience. I also point out that age does not have any significance as it is often the elderly who are the worst culprits.
However, to look on the positive side. In the UK usually people take fairly quick showers, in Europe you can be waiting half an hour while the Italian in the cubicle washes everything at least 6 times, and is usually singing. Comes out smelling like a brothel, but of course I would not really know about such things.
By the way as the protagonist was Scottish you could always shout back 'Away and bile yer heid'. That would probably shut her up.