ACA takes a dim view of employer-provided healthcare. A company is under obligation to provide a health insurance policy, but it does not have to subsidize it. It has to ensure the coverage is "affordable", but considering affordability is highly subjective and since there's already a state or federal run exchange in charge of providing affordable healthcare (it's the first A in ACA), offering a healthcare plan that's equivalent to the one offered on the exchange is deemed affordable enough. Basically, the government entity with its hundreds of thousands of participants is likely to extract a better rate from insurers than Joe's Tanning Salon and Fish Bait Shop in almost all circumstances.

Not sure about the other types of insurance, since an Uber vehicle was not bought by Uber, is not maintained by an Uber mechanic, and is used for other purposes than driving for Uber, it seems unlikely that they would offer more than commercial liability insurance they already offer https://newsroom.uber.com/56463/