I don't know why people keep trying to come up with reasons to try and justify what Apple are doing, if these were the reasons, then surely Apple would have stated them themselves in their defense.
What they said however was:
The underlying economic model in each country has an impact on how we price our track downloads.
Thats not unusual. Look at the price of CDs in the US versus the UK.
We believe the real comparison to be made is with the price of other track downloads in the UK.
Which to me translates as - "everyone else is ripping them off, why shouldn't we?".
Also, as to claims that cars cost so much more in the UK due to having to switch from the steering wheel from the left to the right (or, as a better argument would have been, to cover the cost of producing both left and right-hand drive models), I say: not true. A growing number of people in the UK import cars from Europe, specially ordered with the steering wheel on the correct side, and have to pay various import, shipping/collection and registration chrages, and it still works out a lot cheaper than buying them in the UK.
It really does seem that Britain is charged more for goods in a lot of cases than elsewhere in Europe, and it seems that it's for no other reason than because companies can get away with it.
Hopefully, when (if?) we join the Euro, there will be greater price transparency, and prices will start to fall in line with one elsewhere in the EU.
Apple aren't the only guilty party, but that doesn't mean they're innocent.