@PiousPenelope I was part-time with playgroup plus I ran 3 of the sessions a week, and full time (with a very flexible employer) with PTA. Whilst full time I also did the football stuff on Saturdays on a rota with my ds, and helped out at Brownies and scouts too, even went to scout camp once!
I wanted my kids to benefit from all the enrichment of clubs and groups, and that required me to put my name down to supervise, or make tea, or sweep up, or run tuck shop occasionally, on top of paying the subs.
If its made very clear from the beginning that not only the group's success, but the individual child's place is dependent on parents taking their turn, then there can be no uproar if little Johnny isn't selected to play because his parents won't spend 10 minutes per half term setting goals up, or doing dog poo patrol.
I've absolutely encountered the very entitled mindset of folk who think that a Halloween disco just appears out of nowhere, or that a Christmas fair pops up with a special room for Santa's grotto is set up by the elves rather than literal hours of prep away from school and then in the building days beforehand. I've overheard people slagging the committee off for asking folk to wash up their own cups, or take soiled nappies home, whilst also moaning that we're putting the session fee up by 20p to £2 for 2 hours of entertainment, play, shelter, craft, storytime and refreshments, but absolutely refuse to come a few minutes early and leave 10 minutes before to end to avoid putting the equipment away.
Anything not-for-profit is only there because of a few folk who put in 95% of the work behind the scenes, and if parents/carers aren't prepared to contribute a tiny bit of their time over the course of a half term to make it happen for the whole group, then maybe their kid should be participating.