Not sure about it being money laundering or this being your only worry - what strikes me is that you appear to be able to obtain credit card numbers from other

Not sure about it being money laundering or this being your only worry - what strikes me is that you appear to be able to obtain credit card numbers from other countries with which you are proposing to use in substitute for the persons actual credit card. In any case my credit card is valid in all countries where I see a VISA or Mastercard sign, and I have never heard of ever receiving discounts for using it. If anything some places charge a premium just for handling it, even in my own country. This just seems like you trying to look for a problem to fit your idea. Sorry about being blunt.