Facebook told a subcontractor to pull the union representative (of subcontracted janitors) off work on Facebook's building. That was because he organized a protest against Facebook's demand to work so fast that it made people work overtime unpaid. This is likely to be tantamount to firing him, though perhaps with a legal loophole.

This is one more reason why subcontracting should be limited by law to small numbers of workers doing small total amounts of work.

Not every business is nasty to workers like this, but no business deserves rights the way humans do. Subcontracting generally gives workers less power over their work (pay, schedules, working conditions), even as it reduces the accountability over the business in regard to the work they do for customers. It benefits the business but harms everyone else. So let's forbid it, except for small cases where a full-time employee would simply not make sense.