@LetItGo99
Regular schools don't have this much community engagement and opportunities for relationship building outside of school. An odd PTA event now and then won't create this much community cohesiveness.
This also applies to leavers and families of leavers who stay in close contact with the school once they've left. I.e. some parents continue on the PTA and/or remain involved with events etc. Ex leavers often return to the school to give career talks or get their employers involved in careers fairs, etc. Some schools have active "old pupil" organisations doing annual events, regular leavers reunions etc. That kind of thing is very common among faith, private and grammar schools, but relatively rare among comps. Not only does it provide extra "bodies" to organise out of school activities, it also brings in funds via the school's "charitable" arm, again, common among faith, grammar and private schools, but relatively rare among comps.
At the comp I went to, there was literally nothing going on outside school, I don't even think there was a PTA. I don't recall a single event where parents were invited other than parent's evenings. And once you left, you were basically forgotten, no "body" to keep in touch or encourage you to return to give career talks, or attend any events (not that there were any), and not a single old pupil reunion over the decades since I left.
My brother went to a faith school, and the difference was stark. A very active PTA, almost monthly out of school events for parents and ex pupils raising huge sums of money, parents of current pupils and ex-pupils all encouraged to pay monthly donations to their charity arm (Friends of XYZ school). Yearly reunions. The funds raised were huge, which was ploughed back into the school to buy equipment, sports equipment and kits, minibus and other transport costs, etc.
Yes, it's that sense of community. In the faith school, all that was done by volunteers - the school admin staff didn't get involved, all done by parents, parents of leavers, and ex-pupils but very professionally. Obviously, most involvement was parents of current pupils, but there was also longer term continuity from a few ex pupils and parents of ex-pupils, some of whom remained involved for decades. At every new intake, the "friends" group were in attendance at open days, acclimatisation days, and first day of new term, with stalls selling refreshments, stationery, second hand uniform, etc., and handing out flyers explaining what they do, how parents can help, donation forms, etc., to get the parents of the new cohorts involved from day 1 (or at least aware of them!).
Most comps don't seem to be able to nurture that kind of involvement, which is hardly surprising when they'll usually have a very diverse cohort of pupils and parents with nothing in common besides their kids being at the same school.