Quite right WAV, you shouldn't really answer a question with a question, unless of course you are trying to avoid answering. Yes, I do know how MacColl and others policed it; by having strict and inflexible rules and virtually ostracising anyone who failed to stay within those rules. It was on a very small scale, it didn't last, and proved so exclusive that there are those who argue that the policy did more harm than good to the cause of folk music.
Now back to the question, which wasn't about what MacColl did, it was about what you would do in your proposed world order. I say again; I'm genuinely interested in how you would go about this. You've always been very keen on regulating behaviour, usually citing the UN as your enforcing authority, but I'm not sure the UN would be keen on patrolling pubs late at night to check what sort of music is being played on which instruments, and I guess you would need some sort of local enforcement. How will this be funded? I assume you would need to legislate in some way; do you see playing the wrong music as a civil or criminal offence? What would the sanctions be? The evidence seems to be that regulations without sanctions are generally ignored completely, so I think you ought to be clear about what the penalties are for cultural infractions of the kind you seem so keen to stamp out.
Stu reckons that you will answer by referring to your website, but since I've read it all and not found any realistic and detailed answer, I think you probably need to come up with something new to answer these detailed questions. I look forward to your reply; I have a lot of other questions to follow.