Because if the numbers don't work on overhauling a single block based on the tax revenue generated by that block, they also don't scale up to work if you draw the tax revenue in from "elsewhere." Everywhere else ALSO has its own road, sewer, etc. to maintain, not to mention fire and EMS services.

If either of these roads serve as an arterial, then the footprint of the change is quite a bit bigger and you are correct, we should consider a wider tax base reflecting the radius of the impact of the roads.

If however it's mostly a residential road, which it seems like it might be, then the scalability point being made by the other responses is probably closer to the truth.

Presumably as a nod towards scalability, on the assumption that in aggregate it ought not take more than the entire town's property tax revenue to keep the town's roads in good condition.

Because other areas will have their own projects (definitely, over the lifetime of the loan, even if not right now), and you can’t make one pay for the other to be long-term sustainable.