I hate articles like these, they raise more questions about the article than the topic. People may be getting exploited but they could just as well be making more doing piece work than they could with an hourly wage especially since it is apparently off the books which also suggests illegal immigrant workers but they do not mention that and I would expect that to be mentioned if that were the case considering the agenda this article seems to have.
The big question that this article raises is the one regarding piece work and can California actually outlaw that, I suspect not and businesses just hire people as independent contractors instead of hiring them as employees doing piece work which is also why it is off the books, it is up to the employee to report the pay and get it on the books.