We are not rich. But my daughter has always been responsible and wise on spending since she was a young child. I have never refused her request of buying something or giving her money because she has been reasonable. Couple years ago I gave her access to my Amazon account and she hasn’t disappointed me.
Since I don’t have any reason to believe that she will spend where I wouldn’t allow her, and as Summer before her boarding school started and she wants to often walk to a close-by mall on her own, I just gave her own credit card on my account, which she will bring to the boarding school.