Everything from the hardware, to the permits, but especially the construction.
Local level lobbying also plays a big role.
My neighborhood is split between 2 cities: About 70% is in the first city and the other 30% is on the other. I live in the "other city". My neighborhood was originally wired by the cable company serving the "other city", Year later, another cable company comes along. The first city get completely wired - including its side of my neighborhood. The incremental cost to include my side of of the neighborhood would have been small at the time as all the needed crew, equipment and supplies were in the neighborhood. But the "other city" utilities board  caved to the original cable company's demand to not let the new company in - not even the quarter square mile section of my neighborhood that is in the "other city". Yes, everyone in my section of the neighborhood wrote both the utilities board and the city counsel asking that the new company be allowed to wire our part of the neighborhood. But we were just "a few dozen households" vs a huge corporate enterprise. (At the time, the new company had no plans involving other areas on the borders of the "other city", so the other residents didn't care.)
 Utilities board because they have control over the installation and use of the "utility poles" that carry power, phone and cable TV lines. In theory, the city counsel could have overruled, but that would have been unlikely even if the incumbent cable company wasn't also lobbying them.