How common is it to be in your mid-20s+ and still look like a teenager?

My cousin is 27 and still gets away with using a child leap card as she looks like she's 15-16. On the downside, she's been denied alcohol and vapes in multiple stores even with her legitimate Garda age card and Irish passport (which she has actually lost). A bartender in America even threatened to call the police because he thought she was using a fake ID.