So I'm all for this effort but there are a lot of opinions in this thread that are (IMHO) too simplistic and ignore history.
1. Building more than one version of given infrastructure is often called an "overbuild" and it tends to be bad. Like you don't have two different electric, gas or water companies running a whole set of wires, poles, pipes or whatever to your house. The capex cost of any such network is massive so paying that cost 2, 3 or 4 times for the same number of customers is clearly going to more costly for consumers overall.
2. Utilities, which aren't duplicated, are heavily regulated to avoid monopolistic behaviour as this is the only rational choice. I believe in the US this is Title II for telecommunications at least (which covers landline service). The FCC under the Obama administration did follow through with a promise to apply Title II to ISPs as well, something Comcat, TWC and the like were deadset against as it would obviously impact profits.
The real problem here is that Internet at this point is really the fourth utility and it should be legislated and regulated as such but Comcat et al don't just want to be "dumb pipes".
This factors into the whole net neutrality argument too. Imagine PG&E said that you could only use electricity for Whirlpool branded washers and dryers or if you used anything else the electricity would cost you more. Well, that kind of discrimination is what US ISPs want to be able to do (sadly) and we've already seen this with, say, Verizon throttling Netflix traffic.
3. ISPs have unfortunately been much better at framing these public debates than the other side. For example, in the aforementioned net neutrality debates, ISPs framed this as the likes of Netflix pushing data onto their network for free and they argued they should get paid for that.
The reality is of course that Netflix doesn't push anything. Consumers are pulling data from Netflix. ISPs are getting paid for this too... by the consumers. The ISPs are simply trying to double-dip and get paid at both ends. What's more, stiffling services like Netflix has nothing to do with any notion of fairness. It's just a backhanded way of cable companies propping up their declining TV businesses.
4. Various other models have been tried around the world to solve the overbuild problem. In Australia, for example, the government has tried a strategy where a single entity would own the wires and ISPs could rent those lines to provide services to consumers. To make this work, the entity owning the wires has to charge the same price to everyone, no matter how big or small.
Unfortunately, for a bunch of complicated reasons to NBN (so-called "next generation" broadband network) is going to end up only guaranteeing 12Mbps to each household... in 2017 for probably A$60-70B for a country of ~24M.
5. Building any sort of netowrk like this is what I like to call a national hyperlocal business and the entrenched players are very good at it. To give some examples:
- Getting access to poles varies from city to city and can be hugely complicated;
- Digging trenches can be just as complicated and you might have to deal with a bunch of different stuff in the ground (eg one area has a ton of limestone in the soil).
- Existing buildings once had single-vendor agreements that prohibited new players from providing service there. At one point these were ruled illegal. They've since been replaced by exclusive marketing agreements where, say, a condo building will only ever tell you about one provider.
- Once you've built past a lot of houses it still requires a lot of efforts to connect a new house (we're talking hours). There is a huge manpower component in this. To be already connected to an existing provider is a huge advantage to that existing provider.
6. No discussion of cable companies in the US is complete without touching on the issue of franchise agreements. A franchise agreement is where a cable company agreed to build in a given city and to alleviate the expense they were offered a number of benefits. These could be exclusive rights, ownership of the poles and so on. But to provide TV service, the company usually ended up paying the town. These sums could be significant to the budgets of the towns or counties in which they applied. These fees also discouraged the municipality from being friendly to any newcomer as any such newcomer may mean a budget hit.
Disclaimer: I used to work on Google Fiber.