“Oh, maybe they got mixed up with the visa because language”. No they did not.
“Oh, maybe it’s really difficult to find local talent”. No it isn’t. Not for them.
There are many advantages for them to illegally fly in a whole Workforce. That is why they did it.
“
> A B-1 visa may be granted to specialized workers going to the United States to install, service, or repair commercial or industrial equipment or machinery purchased from a company outside of the United States, or to train U.S. workers to perform such services.
https://es.usembassy.gov/visas/commercial-industrial-workers...
Many of those detained have been reported to be employed by Hyundai's equipment vendors. That would be consistent with activities of this nature.
It's probably a coin flip whether a different DHS staffer would agree, though. Interpretation of these rules has always been notoriously inconsistent, and probably explains the problem here.