Cable built up the outdoor wiring plant by offering a compelling new service (great reception for local TV and exclusive national programming) without significant competition (you could get a giant satellite dish, but compact dishes were not available until after cable was mostly entrenched).

It's not easy to overlay additional infrastructure wiring to compete with existing services (most areas already have good enough internet and video services from one or two providers; especially when a new entrant prompts upgrades from the incumbents). On the other hand, it's very easy to use wholesale access (if available) to provide middle mile competition. You would just need a couple routers (one at last mile provider building; one in a local carrier hotel/colo), a leased line between them, and a transit account.