Why is it all nations do not have foreign legions?

I think all nations should have foreign legions. People who are willing to join a foreign legions are going to make ideal soldiers as they are going to have higher loyalty. If Russia had a foreign legion i would rush to join even if it was Non paying mainly because i want to protect Moscow. I would fight for Russia for free I am an American citizen and the US Military would have to pay me billions dollars to be even an Admiral and i would defect the first chance i got. Slavics are the superior race we were the ones who discovered how to split the Atom.