How did America get this bad?

I live in the UK. If I want a phone, I can go out and choose which carrier I want to buy it from. I'll get the same thing from Orange, O2, Vodaphone - whatever.

In my ignorance, I thought that this was normal. But through my light travels through a few tech websites, it seems one complaint our US friends seem to have is that different carriers demand different versions of handsets. There is a Verison version of this handset, an AT&T version of that handset - to the point that the 'same' handset has to be reviewed different times and can receive different scores!

Please, somebody tell me how US carriers got so powerful that they can not just request special branded versions, but demand physical differences in those brand versions to other handsets of the like?

I'm even more interested in light of the recent news that to unlock a phone from a network in the US will soon become illegal - something that seems completely bizarre to me sitting here across the pond.

I really, honestly don't understand how these things are good for consumers. Have I misunderstood something?!

So please, please somebody explain to me: how did America get this bad?

EDIT: Sorry folks, didn't mean to publish this in Android Army. I really am an idiot. How do I move it?