I don't have any hard numbers, but I'm going to wager that regulatory capture through pole attach rules has way more impact than high initial investment or land

I don't have any hard numbers, but I'm going to wager that regulatory capture through pole attach rules has way more impact than high initial investment or landlords. I've experienced how local governments handle ISP regulation first-hand. I can say with confidence that it causes many, if not most, issues with ISP monopolies in suburban and rural areas in the US.