icloud – how does giving Apple my CCV code confirm I am a parent of my child?

I am setting up iCloud account for my child (just created a family). After setting nickname and entering my child’s data, I am prompted for CCV code for my card, and it says:

“confirm you are the parent or legal guardian of this child by entering the security code for the card, Visa (**** 1234)” – last 4 numbers are from my card.

I can’t understand – how does it confirming I am a parent?! And why is this even needed?