>The service is essentially public, like education, health, and roads.

Could not disagree more. I am not a Facebook user. While I have benefited much from education, health, and roads, and would stand to lose a lot were they not present even if I chose not to use those services. As a non-Facebook user, my life has not been negatively impacted by not using it, nor has it been positively impacted by other's using it.

The value of this service is so low that I would absolutely be opposed to the state getting involved in providing Facebook alternatives, and would really not want my taxes going towards it. Let those who value it pay for it (whether financially or through their data).