I think you are thinking about the pretend scandal of kids providing ONE print of ONE finger in order to buy lunch or show attendance. You provide no context though, so just to mess with your head bear in mind that kids are fingerprinted just like adults when they are suspected of committing a crime, they are also printed when they enter many countries, or even enter this one.
Civil liberties organisations like to make a bit of a big deal out of all this but, as long as the prints are deleted after they are no longer needed, and as long as children know they can refuse to provide a print ... what's the issue?