Most Google contractors are already employees, just employees of some vendor or contracting firm instead of Google itself. I don't think the ABC test prohibits that kind of arrangement.
So that just means Uber won’t allow people to sign up to drive directly. Uber will contract with companies, who allow people to signup. Those companies will “employ” people at the same terrible rates Google contractors get with no medical or benefit of any kind.
It's the same at Microsoft and Amazon. In order to work as a contractor, we need to be represented by a managed service, or a preferred vendor. Some vendors offer benefits, others will give you more money for less of their "service". There is some benefit to having it run like this (E&O insurance, quarterly taxes, group health care).
If you are a contractor, make sure you shop around for managed services. There are transparent vendors out there and some willing to show you their cut (although not many).
For Uber, drivers are not employed and treated as contractors.
For Google, chefs are employed by another company (food services), which has contracts with Google. And also treated as contractors.
I think these two types of contractors are different. Let's say if contractors are already employed and offered insurance and minimum wage, is it ok for them to work as contractors for other companies like Uber or Google?