[MMM]

Just to be clear, stores in America (and Japan) do not prefer credit cards. They prefer cash. All credit card purchases cost the store a small fee. This is why in the US you will see signs that say "No credit card purchases under $10" or "No credit card purchases under $5". You wouldn't see that in Japan because no one would use a credit card to purchase anything under probably 3000 yen. It is silly (in Japan) to think you would have less than that in your wallet.