I think it's probably got more to do with an (understandable!) nervousness by policymakers about what would amount to a second semi-official chain of command in

I think it's probably got more to do with an (understandable!) nervousness by policymakers about what would amount to a second semi-official chain of command inside such an organisation. The union leaders would have an awful lot of leverage over the government and I can't see any politician giving that away willingly.