It's a mix. Some had proper visas, some had "wrong" visas, depending on nuances of what you can or can't do under particular visas, which has a range of ambigui

It's a mix. Some had proper visas, some had "wrong" visas, depending on nuances of what you can or can't do under particular visas, which has a range of ambiguity, and and some had clearly wrong visas. (Or at least that's my understanding.) That said, "willful action on the part of the individuals" is likely not the case - this is a large Korean conglomerate, all of them will have been doing what the company told them to do. This is part of why it's such a big deal to Koreans: workers who were doing what they were supposed to do correctly from a social perspective were treated like criminals, which is a major issue culturally. And the company will probably have understood that the USA understood that for cases where no proper route, or only ambiguous routes, existed, everyone else will be part of cooperatively addressing ambiguity advantageously.