Entire reseller websites (e.g. g2a) of games and software alike have popped up trying to profit from this arbitrage opportunity. You buy games in Russia and an American scoops up the license key for a little more, it’s all automated too nowadays.
On the same note, why are Levi’s jeans $100 bucks in Europe, but $40 in the USA? They’re probably coming out of the same Asian factory. Not an economist but different value propositions I guess.