[user104658]

Ask because all of the big companies use random ID compliance testing and if you have a think 25 policy and fail to ID a 24 year old - even if they're clearly over 18 - you'll be marked as a "fail" and (depending on company) get a staged disciplinary.

It's just not worth it. No matter what the official policy is - if you're front line staff selling age-restricted products, in your own head "think 30" and ID anyone who isn't blatantly a full-full adult. Preferably with a few wrinkles and a grey hair or three.

Yes this means you'll end up IDing a few clean-shaven/skinny 35 year olds... but it's better than the alternative.