What a lot of schools have lost (sacrificed) is proper parental engagement.
Private schools and grammars tend to have strong PTA's, "friends of" groups, alumni groups, which forge strong links between parents, between parents and schools, between parents & teachers, between ex-pupils and current pupils, etc.
Nowadays, schools seem to want to exist in a vacuum and regard parents as some kind of enemy, where contact needs to be minimised. Kids are forgotten (erased from memory) when they leave, never to be seen nor heard of again.
And, no, it's not always about money.
Parental groups and alumni groups often ran/run on volunteers, and put very little strain on the schools staff and other resources, in fact many make a significant net contribution to the school via fund raising etc.
"Out of school" activities like sponsored walks/runs, annual party nights, jumble sales, etc can really bring parents and school management together.
My son's school (with a long history, but still a state school), did a lot of that. It also had an on-site school shop selling second hand uniform and other equipment like calculators, branded pens, umbrellas, mouse mats, mugs, non uniform branded hoodies, etc., revision books, etc - operated by volunteers every Friday afternoon and Saturday morning! They also had stalls at open days, parents evenings, sports days etc., selling refreshments, revision books and calculators. They did a roaring trade on the transition days and first day of term for new starters - selling the "official" school calculator and other Maths equipment (geometry sets etc), second hand uniform, etc., and refreshments.
Their "Friends of" group who did all that regularly donated tens of thousands worth of equipment to the school, things like CAD & other equipment for the tech clubs & societies, a new lighting & sound control system for the drama dept and school hall, sports kits for the school sports teams, etc. Apparently they weren't allowed to buy stuff for anything required by the curriculum, but could buy stuff for things that weren't part of it, i.e. after school clubs & societies, etc, so mostly for "enrichment" rather than exams and league tables.
Because the alumni are also kept in the loop with "Friends of" newsletters, etc., many of them remain active and engaged, i.e. coming back to give careers talks and attending careers fairs, or just attending the social events if they still live in the area.
Like I say, minimal strain on school staffing and resources as it's all done by volunteers, being past and present parents, alumni, and even retired teachers.