That’s a great question. ISO 8601 doesn’t allow timezone offsets on date-only strings.
If you were born in the US, can you buy cigarettes at 12:00 am on your 18th birthday in London?
I’ve never heard of age verification laws caring what timezone you were born in. In fact, you couldn’t even pinpoint this from many people’s ID cards. Plenty of US states span multiple time zones, and I wouldn’t be that surprised if there were a maternity ward out there sitting on a TZ line.
The answer is that no age related verification-problem in real world is so sensitive that a day plus or minus would make any difference. So they skip the entire clusterfuck of a problem of timezones by just ignoring them.
I grew up in a country where you could legally buy beer with 16 and and hard alcohol with 18. So if the answer to "when should someone be allowed to choose to drink alcohol" has a variance of multiple years between countries who cares about a day or two.
If you were born in the US, can you buy cigarettes at 12:00 am on your 18th birthday in London?
I’ve never heard of age verification laws caring what timezone you were born in. In fact, you couldn’t even pinpoint this from many people’s ID cards. Plenty of US states span multiple time zones, and I wouldn’t be that surprised if there were a maternity ward out there sitting on a TZ line.