This doesn't address the parent poster's point:
>For many, it is the only type of job / income they can secure (i.e recent immigrant) and otherwise would be locked out of the legal economy altogether and will transition into the _illegal_ economy for want of options.
Changes like these aren't a free lunch. If they're too onerous companies reduce their workforce, which would leave their workers worse off. Presumably the reason why they were working there in the first place was that it was their best option.