Parents don't bother getting involved until there's an issue du jour. I served on a school board, and it was something of a surprise if we got anyone other than those being paid to be there - school officials and local news reporters. Then, we'd have a contentious issue, people would fill the room, a lot of shouting would ensue, the issue got "resolved" - or not, but we couldn't do anything more about it - and attendance dropped to zero again.
Parents could make a difference if they cared enough to show up to board meetings where these things are discussed before they're rolled out to classes.