Flip it around and look from the ISP's point of view. Once fiber is connected to a house, there are few good reasons to use anything else. Whomever is the first to deploy it wins.

Now look at it from a monopoly ISP's point of view. You're providing 100Mbps service on some form of copper wire, and you're quite comfortable leaving things like that. No reason to invest in new equipment beyond regular maintenance cycles. If some outside company tries to start deploying fiber, and if they start to make inroads, you're going to have to (gasp) spend hundreds of millions on capital outlays to compete with them. Better to spend a few million making sure the city never allows them in.