Your argument is mostly invalid as H&M, for example, has tags in multiple currencies. And as a non-Euro Romanian I can tell you that the conversion rate is not favorable to the buyer.
My point is that for H&M and similar networks the prices are constant across countries, based on their pre-set FX rate, which is not in the favor of the buyer.
The initial argument would only be valid if prices in different currencies would be smaller in the poorer countries, which doesn't happen anyway, regardless of currency.
> The initial argument would only be valid if prices in different currencies would be smaller in the poorer countries, which doesn't happen anyway, regardless of currency.
But it does happen, on average H&M products are cheaper in Portugal than on Germany, except for those few cases I happened to stumble on.