It's not even so much 'as the government has instructed'. The laws around the associations grew around the associations, with much generous assistance and advice from their own paid lobbyists - much as with the darlings of the modern tech industry, in their day the associations were 'disruptors,' too.

When I say 'under current US law,' what I really mean by it is 'until the Sherman Act is applied as written'. It would be nice to think that might happen in my lifetime, but it has been some years since I could reasonably consider myself young.