One important difference is that Facebook is not cutting up streets and accidentally severing other utility cables, pipes etc in order to extend their reach int

One important difference is that Facebook is not cutting up streets and accidentally severing other utility cables, pipes etc in order to extend their reach into target markets. A rival telco would have to do that if it wasn't required to give them access to this physical infrastructure. They are also not using a precious limited resource (such as radio spectrum) that would be spoiled if everyone used it without regard for the impact on other broadcasters and consumers.