Why are Americans such sheep that they let the banks change their aggregate behavior to use little plastic?

One is reason is convenience; not having to drive to the bank or counting money. The other is some people might not feel comfortable carrying a lot of cash with them. If there wallet is stolen they can cancel a credit card or a debit card, preventing theft. Third would be that they don't have the money for it, but they will by the time the bill comes.(credit) Debit only allows you to charge as much as you have in your bank account.