Sure, a couple stand out. First, we were to volunteer a certain number of hours to a parent-run fundraising organization. I forget the actual process of how this requirement worked; except that among the pile of paperwork parents are given to sign was an agreement to do the work. We didn't mind, so we signed and included a list of our skills.
In practice, what happened was that after we had done our hours, they asked us to do more hours. We said no. Then they cajoled us. We said no. They then essentially harassed us and implied we didn't care about our child if we didn't do more hours. We said no, but this still went on for awhile. You can't escape them either. Even after they stop calling, they gossip about you and get passive aggressive at events. I talked to some parents of older kids and was told that the volunteer organizers only ever bother the parents who actually volunteer. They don't bother with the ones who never do their hours because they figure they never will. So these parents just stopped volunteering altogether. After a couple years of this, I followed their lead.
Second,
The school my child attended was in the same physical building and had the same administration as another school. The two schools used different teaching methods. The population of the school my child attended was about 30% of the population of the larger school. Both schools were neighborhood schools. If you lived in the neighborhood and applied, you got into my kid's school. If you didn't apply, you got into the larger school. If you lived outside the neighborhood you could apply for either school, and IIRC, you got in through a lottery process and only if there was room. In practice, no one ever applied for the larger of the neighborhood schools, only my kid's school. Most people just didn't apply, so my kid's school was smaller and about 30% of those kids were from outside the neighborhood.
Each school had its own PTA. At one point, the larger school's PTA approached our PTA about merging into a single organization. It made a lot of sense on paper, especially since there were "all schools" events. So it happened. The president of the larger school's PTA stayed president. Her first act was to send out a letter to all the parents talking about the merger. It also talked about "putting an end to the special treatment of a select few." In other words, our kids weren't going to get their school-specific field trips that were made possible by our volunteer hours and other fundraisers.
The subsequent meeting was eye-opening. They talked as if the kids' of the smaller school were all little Gates, Zuckerbergs, and Musks, even though most of us lived in the same neighborhood and I only knew of one family with any significant money. Most of these people were wealthier than me just by virtue of owning property in the Bay. We lived in an apartment with rent we could barely afford that was larger than a lot of these people's mortgage payments.
What we thought was going to happen is we were going to merge our PTA's hard-fought opportunities with their sheer number of parents to raise more funds for everyone. What they thought was that we had more money because we were rich and it wasn't fair and they were going to take it and give it to their kids.