I am one of the few volunteers on my dc school PTA. We have little or no help from teachers to run any events except the summer fĂȘte.
We try to hold a disco every term where we sell penny sweets (aka haribo I am ashamed to say) and small bars of chocolate.
We keep our unused sweets and chocolate in the store room. We don't always have the same people helping so it's difficult to keep track of what's in there on an ongoing basis. However, I think it's obvious that the stuff isn't the school's as they only have fruit for tuck these days.
We have been noticing that our stocks aren't going as far as usual and head said yesterday that she had caught a teacher a few times coming out of the store room eating our chocolates. It seems this has been going on a while.
By the way us volunteers are always scrupulous in ensuring we always pay for anything we or our children have. In fact we don't ask for for any expenses like phone or paper ink laminating sheets etc
So AIBU to be pissed off with this teacher and to think if she did it in a shop it would be theft and the fact it it the pta's is irrelevant.