You are incorrect.
The workers they brought over were not allowed to work in the US. If they had been on H1Bs, they would have to have been paid competitive rates for skilled workers (you can't bring over H1Bs unless they have skills you can't find enough of in the US) so they must be worth $20 an hour at least. If the workers had had real work visas they could have gotten low skill jobs which paid a bit more than minimum wage and would have gotten overtime, would have had some rights, could have negotiated with their employers, gotten raises, changed companies, etc. Certainly they needn't have worked for EFI and gotten minimum wage and no overtime.
So this company didn't save $40,000. They saved more than $80,000. And the government looked right at them and yet still somehow managed to look the other way.
So your points are logically correct, but they save more like 40 cents on the dollar even if they're caught 100% of the time.
Yes, jailing EFI's board of directors would be a start. They are responsible for the company and ultimately, if you can't figure out who really broke the law here, they're responsible. They are also the most likely to affect change, once they get out of prison.