The same argument could be made against the US federal government. Two points:
(A) unified legislation is tremendoulsy important for trade/business (B) larger associations have far more influence than small ones.
I don't see any indication federal government is more resistant to regulatory capture than state government. It may be more expensive, but the numbers are still don't even breach 1% of potential profits, and capturing one federal regulator is much better and easier than capturing fifty+ state ones or ten thousand local ones...