[gamblor956]

The law allows for veil piercing in situations like that, meaning they could skip the temporary intermediaries and just treat Uber as the employer.

Believe it or not, they did think of issues like this when drafting the law. Especially since almost all of these other issues brought up in the comments are decades old and already addressed by existing labor laws.

[quaquaqua1]

That was not immediately known to me, because in New York where my family member is a lawyer, something like the following will happen:

Company X owns Company Y. Company Y builds an apartment building of low quality and hides the defects. They sell the apartments to individual buyers.

The individual buyers sue Company X years later upon finding the defects. The judge throws out the lawsuit and says "you can only sue Company Y, because that is the legal entity who built the building."

The only issue is that Company Y is several million dollars in debt to Company X and has absolutely no way of repaying anyone who sues Company Y.

[bernawil]

Others are pointing out the problem with staffing companies too, but this reminds me of my experience (different countries, so YMMV). This means that even though "The law allows for veil piercing" there's a huge maybe there, companies unloading their liability know this and have great lawyers. So IF a lawsuit gets to the real employer it's only after a LONG legal process, so not worth as much.