I mean, sure, I never disputed that (because I have zero idea how difficult it is to buy a knife in the UK, and I’ve never even said anything about knives).

My question was about the stricter limits on purchasing alcohol or lottery tickets in the US (which were brought up in the comment I originally replied to), because that was the first time I heard about that. I was curious what those alluded-to limits were, and I still have zero idea.

They're probably referring to the fact that you can buy alcohol at the age of 18 in the UK vs 21 in the US. It's also much more easily accessible, for example, we don't have dry counties or state-run liquor stores.

Bars in the US routinely ID people who are obviously over the age of 21. And then they get weird about foreign passports because...well, because America, I guess. I've sometimes been refused entry despite being clearly over 21 and having my passport with me (or, absurdly, been asked to show another ID, as if a passport wasn't sufficient for buying a beer). Attitudes to IDing people for alcohol are much more pragmatic in the UK.

Generally if you look over 25 in the uk you don’t need ID to prove you are over 18.