Seems to me the only reason to legislate further is to provide a means to prosecute; those who break the existing limits will continue to do so, until they grow up or are killed, while those who are wiser will continue to operate sensibly.
I think the original poster's 'bloke in a pub' scenario is as far as any change has got - alcohol is out of the system by 12hrs, and an arbitrary figure of 24hrs has no basis to be any better than, say, 16hrs. That said, their airships are unemployed enough to bother themselves with more trifling matters, such as issuing diktats about blue uniform, so I won't head down the bookies just yet, to place my tenner on this being made-up.