The worst I've encountered of this type of head-in-the-sand logic was in NZ. They have a law that if a person buys alcohol with companions, the clerk will check the IDs of all of them, not just the buyer's. Presumably this is to stop underage kids having an older friend buy them booze. In reality obviously, teens without IDs just wait outside and literally 100% of the times this law is applied is when an over-age-but-without-ID is accompanying someone shopping for some dinner wine. Like me and my ex gf...
I had something similar at a liquor store in Utah.
My mom (well over 21) tried to buy liquor, but was refused because a lack of ID. She sent me (also well over 21) to buy instead. At the register, I made a passive aggressive comment about how my mom was refused 30 mins ago. So they refused ME because they wanted to "ID all people at my party" - or something like that.
This is standard practice in the UK too - if you're buying alcohol as a group, they'll ask for everyone's ID if any of you look too young.
But this isn't specifically written into the law, i.e. the law doesn't say "you must check the ID of everyone in the group." Rather, it's that businesses receive ENORMOUS fines if they're caught selling alcohol to underage people - so most of them have very strict internal policies to minimise the chances of a false negative.
