What do you mean? 'mericans earn more (much more) than in many places in Europe.
Notwithstanding the massive generalization you just made, 1:1 pricing in comparable but not identical currencies isn't all that unfair, as wages are treated similarly.
A person doing my job in the EU or Britain tends to make the same number figure of money, but in their respective currency (rather than CAD, in my case). Thus, while we retain the same income status so long as we remain in our own countries, Britons or Europeans suddenly find themselves a lot richer when they come to North America, while North Americans find themselves a lot poorer in Europe. Pricing and wages are largely the same numerically relative to their economy between USD, CAD, EUR, and Pounds, regardless of currency exchange. That's why it's not really fair for me to think of my wife's British relatives who make X pounds a year as making roughly 1.5-2X what I do at $X CAD (which when exchanged, it is), as their pricing is done accordingly.
EDIT: I should mention though that I think pricing *SHOULD* be set based on cost of distribution to market. As a Canadian, I get regularly gouged based on some mythical exchange rate between USD and CAD that hasn't existed in 10+ years.