I find fiber to be most rare in recently developed suburbs (1980s to 2000s) with buried utilities. It is too costly to dig and lay new fiber to the home underground.
Stringing it along existing poles is cheap, and installing it in new underground utilities is cheap.
> It is too costly to dig and lay new fiber to the home underground
Digging is not required in many locations. Citywide rollout in Christchurch (400k people, low density) mostly used horizontal underground drilling: https://www.youtube.com/watch?v=TzGZl0jKRS8
New Zealand (similar size & population to Oregon) with a population ~5 million, used a lending model to fund a national fibre rollout in a private-public partnership. The Government lent money, but expected the project to have a final cost of ~$500M USD after loans repaid in 15 to 20 years. https://archive.vn/20170807221541/http://www.stuff.co.nz/bus...
84% of NZers can access fibre, and uptake is 64% and rising.
Faster internet for residential service also requires faster interconnects. It requires public infrastructure, residential modem upgrades, residential line installations, backhaul and datacenter hardware upgrades, new servers to mine all that extra data, more expensive equipment to fix/repair line breakages, and better trained technicians who also understand fiber too instead of just copper.
Why waste money on that when the plebs are perfectly "happy" with ADSL or cable and pay a hundred bucks for shitty service and almost zero human support?
Stringing it along existing poles is cheap, and installing it in new underground utilities is cheap.