My guess is that in a true free market, a big chunk of those households would have no cable service at all. That is to say without the franchise agreements that gave them quasi monopolies in those areas, providing service wouldn't have been attractive in the first place.
Remember when there used to be five different cable companies listed in the weekly TV listings? Maybe you never saw that in your area, but when I was growing up in a semi-rural suburb, there were many cable TV competitors. Surely they didn't all require franchise agreements to want to enter the market.
Further, assuming franchise agreements exist and were necessary, consumers and municipalities should expect better from their franchisees than abuse of monopoly.
You're totally ignoring the difference between cable systems now and cable systems back then. Building modern HFC networks capable of supporting broadband requires tremendously more investment than cable TV systems of yore.
