Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Why don't banks allow more control over credit/debit card charges?
quid has expressed some of the disadvantages with this approach, but there is another. Vendors will not want to give you any goods you buy with your credit card until they are sure they will get the money. With your suggested approach buying something with a credit card now looks like: No vendor is going to stand for this for even moderate sized transactions, so in reality they will just decline your card if you have this facility enabled.