When an ISP runs fiber to a new building (be it in a business park or rural farm), the math is almost entirely based on recuperating their installation costs - which they often pay for entirely out of their pocket. Your entire first contract term is usually just paying back the installation costs alone...
For some perspective, at a previous building we tried to bring fiber across the street into our office. The installation costs were too expensive to make the math work - so the ISP offered to split the installation costs 50/50 instead. Our half was over $94,000. This involved directional boring and the works, to go ~200ft to the right-of-way vault and into our MPOE.
One can only imagine the expense of running fiber (or any type of cable) out to the boonies. It's totally feasible - but the costs make it not palatable in reality.
Running a fibre is about the same cost as running a power cable.
There is a lot of infrastructure where the cost to replace is an order of magnitude higher than the inflation adjusted original cost.
No free lunch, as they say.
Source : https://internet.buildns.ca