There are at least 3 major nationwide providers competing against each other on service and price. There are also many secondary local providers and providers renting networks from the national providers.

How is that not competitive?

You can't take a unlocked GSM phone onto Verizon or Sprint. You can't take a Verizon phone onto Sprint. You can't take a Sprint phone onto Verizon.

The only carrier you can choose with GSM is T-Mobile. But wait, they use the 1900MHz 3G band, so if you've got a phone that doesn't use that band, you're stuck with EDGE data.

LTE won't change this, they've chosen different bands.

You can however sell your phone and buy one for a different network. iPhones in particularly have a very high resale value, and regardless the phone you bought maintains its market value and is resalable.

Telecom networks are extremely expensive to build. Having more than a few on the same technology would be wasteful, and consumers benefit from a diversity of technologies in the long run in addition to some level of network compatibility.

But seriously, don't like your network? Sell your phone on eBay and buy a different one that works on a different network. How hard is that?

"Competitive" is not binary. Yes, 4 networks is better than 1, but it's not like you have 30 choices.

Even with MVNOs, there aren't many real options. If Verizon were GSM it'd be a lot better, but as of now you are really locked in.

Your phone is freely salable. You are not locked in.