You can tell a child from an adult at first glance, right?
Here you see one child and two adults in the foreground. No confusion.
1) 
You can tell a child from an adult at first glance, right?
Here you see one child and two adults in the foreground. No confusion.
1)
but cashiers at supermarkets are told that they have to ask for the ID of anyone who looks 25 or younger.
Why? If minors are children it should be totally obvious at first glance. Wait, you mean that in the checkout line at Kroger's a 16 year old might pass for 26?
2)