I don't have the answer, but I wonder if they are considered a utility and operate on utility easements. Then we have to look at the county and state, too.
On the other side, I've read they operate a considerable number of private installations, too. Even that is suspect, too, in that there is existing case law affirming that people have a reasonable expectation of privacy in "the whole of their public movements."
They’re not utility. But you don’t have to be a utility to construct in the right-of-way.