True, but if it was regulated then they wouldn't be able to buy it if already drunk.

I've always assumed that if we were going to legalize it we'd want to do it properly and make it as widely available as alcohol ie carry-outs. I'd imagine that's the only way you'd stop the illegal trade of it, which I take to be the most important aspect for this country

Then if it were taxed you could get the customs and excise to deal with it, plus they have more powers of entry than the police. Having taxes involved could make it expensive to deal. Tax fraud can carry increasing penalties.

Still requires the police as 'backup' (in that sense), not to mention a severe increase in funding for both... and assuming they don't try to kill each other over the 'glory'

Not necessarily. The revenue raised might actually reduce the needs for cutbacks. There has been no problem about splitting the glory, the police still arrest but customs gets them through the door.

What, selling the 'good sh1t'?

CID and Special Branch (or whatever they're called this month) don't get on historically, and cases can take months, never mind bringing in Customs more...

I think that might be more down to empire building. Special Branch always need an enemy, to justify their existence. CID screw up cases without any involvement from third parties because of incompetence. That will still be the case.