I have not seen any evidence that South Korea is a "lower cost economy" or that the Yokohama (now Shinko) brand was made to "lower" standards. If there is any such evidence, I'm sure we'd all like to see it.
It's a popular conception, and in many cases true, that Asian products are inferior. Still, ALL manufacturers build to a specification, and that specification is a company target, not a regional or country-specific one. Asia, India, Eastern Europe, any or all can produce world-class product, if that's what the buyer wants, and will pay for.
I wd prefer to buy tires and rims made in Canada or the U.S., just to avoid the wasteful practice of sending stuff all around the world on ships fueled by the nastiest stuff imaginable, but that's just not happening.