Yes despite my downvotes I’ll stick my neck out to agree with you.

If a US company wanted to sell liquor online in the UK, they’d have to follow U.K. laws for alcohol licensing and age-verified delivery.

I don’t know why age verification is any different. That’s the UK law (which I disagree with for what it’s worth, certainly in its current implementation) and if you want to operate in the UK (and for a website that means be accessible to U.K. audiences) you follow U.K. laws while here.