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.