It isn't that simple so please stop having a go at her.
My child managed to buy several things the other week through Google Wallet which I had NOT activated on his tablet.
I had used it once online about 6 months previously, to pay for something on a website that didn't accept anything else.
They transposed my card details onto the tablet without my permission (I checked settings - it said I had not activated google wallet on ANY device) and also, even though it is password protected to the max, I had not realised that in the small print (where do you even FIND that) is a clause allowing purchases without a password for 30 minutes after the password is put in.
These things are a learning curve. Children are less likely to understand how clicking on certain things is not going to achieve exactly what they think it will (ds clicked on 'buy' to see the prices, not realising it would actually go ahead and buy this crap)
he told me immediately, it was a genuine error and made very easy by the app design. I do believe that some are designed to trick you.
They were using my debit card details though to ask him if he wanted to buy things, and I had never entered them onto the device...it's because it was set up using my gmail account.
I had no idea they could take this info and enable purchases with it on a device you had never used it with.