Because we buy that stuff even without it. And if you make both good and crappy products, why sell the good stuff internationally?

The US did it when it was a bigger steel supplier, good steel was sold domestically, crappy steel was sold elsewhere. If you got crappy steel in Africa at the time you might have thought US steel was garbage with poor QA, but in reality US steel was great and they just shipped the crappy stuff because people still kept buying it.