Yeah, it's always interesting comparing drinking laws. In the UK we've tried to crackdown on underage drinking quite a bit in the past decade or two. But it hasn't really worked particularly well. Part of it is that in their crackdown on drinking, they've massively increased the taxes on alcohol (as if price will stop people partying!). These have really squeezed the little country pubs so much that roughly 30 pubs are closing down every week now. You may think that this is a good thing on the surface, but all it does is drive people (and kids) from the small safe pubs in the villages, to the big venues and clubs in the towns and cities; which are open far later and push far stronger alcohol to maximise sales. And it's the concentration of people in the major drinking towns that leads to a lot of the disorderly behaviour, violence and accidents requiring A&E.
Whereas 20-30 years ago, small village pubs were a mainstay of drinking culture. Turning a blind eye to the occasional kid drinking a pint or two was a heck of a lot safer than pushing them into the cities with fake IDs. Or buying litres of spirits and downing them on a park bench. But pubs can't afford to take any risk nowadays, for each 17 year old you accidentally let into the pub, it's a £10k fine for the manager, £5k fine for the barman who serves the kid. Plus a possible revocation of license.
Then there's the social downsides of being too strict on drinking for the rest of us. The "Think 25?" campaign is particularly terrible, it catches even people like me at age 30. I can understand that maybe I look under 25, but do I really look 17 years or less - that's what the law says they have to legally look out for after all. That is my legal right. It's insulting and an infringement on basic liberties that we should be able to take for granted. I envisage having to carry ID on me for a good 5-10 years more, unless I grow a beard...