Except that Europe does pay. It’s just that Russia wants them to break the law and pay with fake money instead.
For the Russians, the Euro is fake money because the Europeans won't let the Russians use it. However, there is no impediment to anybody using Rubles, so the Ruble can be considered non-fake money.
In the greater scheme of things, if a contract transaction can't be made in one currency, the world requires that we use another. A contract is an exchange of one thing for another. There is no such thing as a legal contract in which one party gains and the other party does not.
(Try buying a car from a dealer then not handing over the cash to that dealer. You could say "I've paid you the money, I'm just holding it for you at my bank." See how far you get with buying that car.)
Try buying a car from a dealer that insists on paying for it in cocaine.
Not exchangeable... by whom? Maybe you might not be able to, but there is a whole world out there that is separate from you and which has no trouble at all.
The 'Western World' is merely one-eighth of the 'Real World', but its population is too parochial to understand that.