In part it's due to prices in the US generally being advertised exclusive of sales tax, which varies from state to state. In part you can blame the higher costs of doing business here (and therefore higher cost of finished products) due to the mountain of regulation and petty bureaucratic red tape imposed by the good old EU (though the British government isn't above blame in this respect either).
The business climate in the USA is simply better than it is here and consumers benefit from it. If you want to do something about that, consider voting UKIP next month.
