Ease of doing business report only deals with formal legal requirements and paperwork, but running business is not only about law/tax compliance.
Access to labour, facilities, depth and readiness of local market to accept new things - all that matters.
I am not agreeing with assessment that legal compliance in USA is easier than in China at all. USA has hideously complex tax system, you can't do a single thing without a lawyer, and any dealing with securities is past all hope for a person who have not purposefully studied that.
The idea that China is the most protectionist country in the world is no more than a meme.
Ranks of ease of market entry are very objective proofs of that.
It gas been definitely easier to setup a viable business in China than in US for a few years now.