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

How can I stop a merchant from charging a credit card processing fee?
Mastercard rules also prohibit asking for ID along with the card. Yet, when I was at Disneyland, years ago (so I don't know if this is still a practice) they asked for my driver's license with every purchase. I can charge up to $200 at Costco with a swipe, not even a signature, but a $5 bottle of water (maybe it was $6) required me to produce my license.  The answer is Pete's comment, don't patronize these merchants. By the way, it's legal now. From Visa web site -  Note - 9* states still prohibit surcharges, so they tend to offer cash discounts. The question you linked is from 2010, things change.