There may be some amount of this due to government control of right-of-ways.

I think economics plays a far bigger role. It is EXTREMELY expensive to build out the last mile infrastructure to provide internet access to people's homes. This is why rural areas have basically no good internet options. Each provider could compete but in order to make their infrastructure investment pay off they have to achieve a particular subscription rate. If not enough people subscribe they lose money and the business folds. So the major internet providers (And I'm not exaggerating) have basically agreed not to compete. They build out a territory and everyone in that area has to subscribe to get internet access it's easy to make a profit.

Right now Google is the disruptive player in the space. Watch the way the incumbent ISPs in the area are freaking out. Google isn't a telco who has been part of the collusion for years. The existing players have tried to deny them access to public right of ways. They have offered better cheaper services, etc... Local governments are BEGGING Google to come. They are clearing regulatory hurdles and making it easy and cheap for new good options to go in and so far at least it seems to be working. We'll see what the future holds.