I lived in the UK through 2007, and the market for phones evolved very differently there.
In addition, the UK benefits from a much denser distribution of population, which helps keep costs much lower in terms of service provision. The Big Four here have to light up a lot of corn fields and desert with 3G and 4G as a condition of spectrum access. If the "USA" consisted of only states ranging from Maryland north to Maine, prices would be a LOT lower, since the coverage would be clustered around DC, Baltimore, Philadelphia, NY, Boston, Hartford, Pittsburgh and Buffalo (the big cities), and the "empty" parts would be a lot smaller.
Meanwhile, poor US carriers have to light up huge swathes of farmland. A T-Mobile tower in Manhattan might service thousands of subscribers, but a similar tower in downstate Illinois or central Nebraska might service only a dozen or so. That cost gets passed on.
That dynamic also impacted which technologies were deployed. While dense and geographically small Europe could get away with smaller GSM cells, the big empty parts of the USA were better suited for CDMA (which has greater range of the two 2G technologies). That's why a majority of US users are still on CDMA... it was easier and cheaper to cover a large, empty area with one or two CDMA towers than six or more GSM towers. But it meant that handsets on CDMA are locked and don't have the economies of scale necessary to deliver much lower handset costs.
Of course, now in 2012, CDMA is more an albatross than a benefit thanks to HSPA+ WCDMA (which has the same benefits of CDMA but works on GSM SIM principles/handsets).