> In Europe customers buy handsets and the carrier contracts separately, and carriers cannot refuse service to anybody who pays and has a handset following the standard for telecommunications.
That's only partly true ... not sure which part of Europe you are talking about but here in Austria it is like that:
You *can* buy a phone and a contract separately or buy a locked phone + contract from a carrier.
In the former case you have to pay the full price of the phone upfront but the contract will be cheaper and your phone will be unlocked.
In the later case you get the phone from the carrier at a subsidized price but get higher rates for your contract, a locked phone and usually can't cancel the contract until after 24 months. If you want to unlock your phone you'd have either to wait for 24 months and pay a small fee or some allow the unlocking earlier but charge a rather large fee for that.
As for the "carriers cannot refuse service to anybody" I don't know if they cannot do that (i.e legally) but they would be stupid if they do given that they would just lose a customer to the competition.
What is that much different in the US?
In the US I have just used prepaid phones from carriers (never stayed long enough to need a contract).