I don't see why its a good idea for urban Americans subsidize those in rural areas. Things like cheap broadband and communication bandwith in general, is an added reason for people to move to the cities. By forcing urbanites to subsidize rural people, we are causing a missallocation of resources.
Of course the broadband tax may only be a few dollars a month, so it by itself doesn't mean much. But I've seen this type of thinking in quite a few areas, and it does start to add up. Anotehr example is electricity where it is much cheaper to bring electricity to metropolitan Americans, but they end up paying the same flat rate as rural Americans anyway.
It's cheaper in a large city because the provider doesn't have to trench a single wire dozens of miles to one single person's home. Fiber is ridiculously expensive, which is why you don't see a huge movement to start laying down fiber to every home or business in this country. They could do it, but the providers would still end up passing the "savings" onto the customer.