While I agree with you that parents have the last word (although that is legally changing in CA when it comes to medical decisions) players/parents usually don't get to choose their HS Coach.Parents still have the responsibility of their children regardless of the coach.
Parents don't hand over that responsibility just because of a coach.
Parents are the people who pay for the teams their children play on. There is no coach that can influence Beyond that parental decision.
Stop blaming coaches for what people choose to do or not. AKA what team they play for: there are plenty of silly coaching things that happen regardless of Fielding mask topic. Ultimately the decision of who to play for is still the parents!
Its funny. In CA base coaches are required to wear helmets when on the field, but the same coaches tell players (including pitchers) they don't like fielders to wear mask because it looks weak.