I doubt the Hyundai employees were even H-1Bs themselves.

They were illegal aliens here under the S. Korean visa waiver program. You cannot work here under a visa waiver status, nor can you stay longer than 90 days. You can be here for business, but not to work. And being here on business means something like attending a sales meeting, visiting a parent company or subsidiary of the company that you work for, etc.

These workers were correctly removed from the U.S.