Social media is not the Internet, but I think you are raising an important point. Schools are run by uninformed people, who introduce absurd policies, when it comes to prerequisites of usage of online services. It is hard for parents to get to their right of not having to participate in these disservices.
I imagine in the US there could be cases, where parents with the required pocket change can sue the school or something, to get it done, but if I think about my own home country, I have my doubts, whether anything would be resolved, before the time of a child in that school is over and in addition to that, there is no accountability for abysmal tech decisions in institutions such as schools. No one is losing their job for forcing children to use social media, unfortunately, even though every adult, especially one to work with children, should know by now, that this cannot be conforming with data protection laws. We simply punish incapable reckless behavior way too rarely.
I imagine in the US there could be cases, where parents with the required pocket change can sue the school or something, to get it done, but if I think about my own home country, I have my doubts, whether anything would be resolved, before the time of a child in that school is over and in addition to that, there is no accountability for abysmal tech decisions in institutions such as schools. No one is losing their job for forcing children to use social media, unfortunately, even though every adult, especially one to work with children, should know by now, that this cannot be conforming with data protection laws. We simply punish incapable reckless behavior way too rarely.