I don't think that prices should be the same, just similar, and I don't think I am being naive but I am happy to let you have your opinion.
Taxes in the UK may be a bit higher than in the US but it is naive to suggest that this accounts for the gross differences in pricing. Let's forget about Bill Gates. Many of the larger US software companies have been asked to explain the gross price differences by PC magazines and they waffle on about this and that but they seldom use local taxes as their excuse.
Why? Because they know this is quantifiable and hence too easy to defeat their arguments.
Added: Oddsod the case you quoted was almost eight years ago and it applied only to PCs, not software. PC prices are not the problem. Why? because we also produce them here and there are hundreds of worldwide manufacturers in competition with each other. The same cannot be said of products from companies like M$ and Adobe.
[edited by: BeeDeeDubbleU at 11:55 am (utc) on Feb. 1, 2007]