Earned is not the same as received. Your child might reach ice cream at eight in the evening, so the app does not pretend it has already happened — it tells them it is waiting for them, and puts it on your You owe list.
If there is another grown-up on the account, they are told right away, so whoever is going to hand it over knows.
Pressing it twice by accident, or on a slow connection, does not charge the prize twice.