I introduced it to my nephew when he was 12 and he succeded to create pretty efficient flying bombs. A kid can grasp the concepts involved at 10, they can surely have fun before but probably more by exploding rockets and messing around with kerbals.
In France we have 3D Secure, when you make the paiement you are redirected to a page that belongs to the bank, you receive a SMS with a one time code to validate the paiement and are redirected to the merchant with the validation.
Quite efficient, but I think there's fees for the merchant in this case.
Also we already consume more than we should, if we go back that would impact the GDP.