direct copy&paste from the Photoshop forum:
do we have to go through this every time a new version comes out? *sigh* Think! --> taxes, customs fees, other distribution cost, accounting cost, compensation for exchange rate losses and so on...
The user-to-user forum isn't the most productive place to have this conversation. I recommend that you have this conversation with Michael Coleman, the product manager for After Effects. Here's a link to his blog.
Another thing that Adobe France customer service told me when I had such complaint when CS4 arrived, is that Adobe France was a private company franchised Adobe and not a "real" Adobe headquarter. So they also have to pay fees to Adobe to be able to use their name, and these fees are of course reported into the price of products.
Maybe that's the same in UK.
The official explanation from Adobe about this concern, which has been addressed at every upgrade announcement for years, is that
(a) there are higher duties, taxes and tariffs in UK & Europe
(b) the European versions of the software bear the additional cost of multiple language versions. The cost of converting to multiple European languages is built into all versions sold in Europe/UK.
And as with almost every major company $1 == 1€