Why do I have to be yelled at?

Why is it that when I ask for age verification, people who are trying too hard to act mature just get angry? I'm just doing it because there are penalties and other issues if I sell to minors. I wish they'd stop with the 'Can't you tell?' attitude. If you want to do that, dress a little more maturely. Anyway, there's no reason for me to be yelled at.