Folks who are mostly interested in broadband are probably unfamiliar with video franchising laws. Many people still apparently believe that cable companies are able to get exclusive franchises from the city (granting them a monopoly on providing cable television). However, that is not true and has not been true for many years.
Most cable companies still have a de facto monopoly because it is extremely difficult to overbuild an existing cable company - the incumbent has most of the advantages and building a citywide network is extremely expensive. This is not a naturally competitive market; it is actually a natural monopoly.