One theoretical framework that justifies regulating telecoms, but not necessarily Facebook is that telecoms usually have special privileges granted to them by governments, up to and including monopoly status.
Building the hardware layer for a telecom network requires access to public land, and often private land where the landowners may not be cooperative. In exchange for the government enabling the telecom to build its network, the government gets to impose rules, sometimes even mandating competitor access to said network.
Facebook is different. The internet is already there, and is not owned by any single entity. Facebook does not need to compel cooperation from anyone to operate. It does not invite regulation in the same way a telecom does.
Now, there are plenty of people who believe that anything is fair game for the government to regulate if it's in the public interest, but I think that position is less universally accepted than that of trading special privileges for regulation.
Building the hardware layer for a telecom network requires access to public land, and often private land where the landowners may not be cooperative. In exchange for the government enabling the telecom to build its network, the government gets to impose rules, sometimes even mandating competitor access to said network.
Facebook is different. The internet is already there, and is not owned by any single entity. Facebook does not need to compel cooperation from anyone to operate. It does not invite regulation in the same way a telecom does.
Now, there are plenty of people who believe that anything is fair game for the government to regulate if it's in the public interest, but I think that position is less universally accepted than that of trading special privileges for regulation.