The huge barrier to entry for cable, water, electricity, and telecommunications (for now excluding cellular) is building the infrastructure. There are good reasons why most of these are heavily regulated.
It's funny you say ISPs because in the dial-up age there were a ton of them. They were working on top of the highly regulated phone system. Fast forward to the broadband age, which sadly was give a lot of free reign under the regulation-averse Bush administration, and there are very few 'ISPs'. Instead most markets are given a bad choice between oligopolistic cable companies and a baby bell or AT&T itself.
These companies have way too much market power, people routinely get cable tv in order to get a decent internet monthly rate, and regulation could have huge benefits for consumers as well innovative businesses like Google.