Anger is pointless without action. Either accept the situation as it is, or start regularly attending school board meetings. If you want a policy changed, speak out about it. Don't just give them vibes either, give them good reasons to change the rules and processes. Have a solution at the ready which is idiot-proof, accessible, and well-supported. Oh, and also, make sure that your clear solution is zero-cost, which is why schools fell into using Facebook and municipal groups used Twitter.
If you want to change the situation, you have to understand why it became the way it is and address the pain points that led here, as well as their pain points that both prevent moving and/or encourage moving. If Facebook suits the needs of the school and the majority of parents, stop being angry and realize that there's a value in the platform for the purpose.