I think it's also important to amortize construction costs over the useful life of the infrastructure, not just how long it takes to pay back the loan. That $4

I think it's also important to amortize construction costs over the useful life of the infrastructure, not just how long it takes to pay back the loan. That $40k of road is only $800/year over 50 years. (And I doubt all of it was even originally as expensive as your estimate, especially considering cost of land, which was closer to zero before there was a road there). Of course, maintenance costs have to be counted, too, and in the case of fiber, it would, instead, be eventual upgrades.