I remember buying a fake ID online over 20 years ago. It didn't work. Even back then pubs and clubs would only accept a driving licence or passport and so your only hope was finding a pub with no bouncer on the door and lurking in a quiet corner while people who were over 18 bought the drinks.
I later worked in pubs and bars and had it repeatedly drummed into me that if I served someone who turned out to be underage the establishment could lose its licence and I could be fined £1000.
It was eye opening the number of adults who blatantly tried to buy alcohol for their children. We had to be hyper vigilant. There was the time I served four pints to three middle aged men and then 15 minutes later saw them drinking with a lad who didn't look older than 12. Then there was the time a man at the bar asked his daughter what she wanted and she whispered in his ear and he said, "A Smirnoff Ice please", so I asked if she had any ID and he said, "The Smirnoff Ice is for my wife, my daughter wants a coke", and then I had to send my manager over to take the Smirnoff Ice off the teenage girl two minutes later. It was really tiresome.
Yes the rules are strict. Too strict, in my opinion. They are part of the reason for a binge drinking culture among young people who go from not even being allowed into a pub on a Saturday night to have a lemonade one day, and being full legal adults the next day. This is why some 18 year olds end up getting their stomachs pumped in Freshers Week.
But for the staff working in these places, most of whom are on minimum wage, it really isn't worth the risk and you are putting them at risk of losing their jobs and having to pay large fines if you try and trick them into serving your children alcohol. Just stop it. The child will be 18 soon enough.