are you sure the US price inc taxes? I can only quote for Canada as with Atlantic Canada's 15% HST vs our UK 20% VAT there's not much in it:
$CAN 699 Plus 15% tax (yes varies by province) =$803.85
[perfect] exchange rate 1.58 equiv in £GBP.. = £508.77
£GBP inc 20% VAT = £529
anyway fyi as I did the sums, here they are.. I've not considered equiv earning rates or sizes of economies or varying tax rates or locale, or free delivery etc etc so this is
no argument of any kind, but just an observation; my personal observations over past 20 years working /living in UK, USA and Canada would be yes in the past rip-off Britain was alive and well but nowadays the gap may not be anywhere near as much as it was.
on some things

in fact we have found now back in the UK how cheap food/milk/clothes/postage is here soo...
anyway, its still a shed load of money for any of these level of phones!