I am part of an amateur panto that has around 70 people on stage and around 30 behind the scenes in various roles, including 3 children's chorus groups.
It always has been asking parents and other connections if they can chaperone rehearsals, make props, etc.
We're moving on to a situation where we are going to be saying that if your child is involved you will (barring exceptional circumstances) do something.
For example the last three years I have washed and put away the entire costumes for the cast. We've put out appeals to help and very few people come forward, I think it was 2 people one year, 3 on the other years. Out of 100 people.
The same people end up doing multitude of tasks. Some parents are very helpful and always willing. Others will do anything to avoid it. For example we asked 3 years ago for the older children's chorus we said we'd ask each parent to stay and help for one rehearsal.
Out of 12 children, 8 parents "couldn't". Excuses varied from "It's my night to play netball" through to much weaker. So those parents were offered the chance to do other things (like wash costumes) that could be done at home. One parent said they would and did it. Two others said they would and didn't, and the others just said that they hadn't time.
We do take advantage of known expertise. I think that's reasonable. Sometimes we offer a free ad in the programme (eg our scene painter has one).
It irritates me that parents are very happy to bask in the benefits of their children being in it, but very reluctant to actually help. Because so few are willing to help, I end up being committed far more than I would like to be at times. Our house is taken over with costumes, and costume making, we can't go away at the weekends-the children have missed things they want to go to simply because if I don't chaperone then the rehearsal can't go ahead.