Look at your costs, including card transactions fees, and spread that across your pricing. It's no different than pricing in all other business expenses - do you complain you're paying a "toilet tissue tax" because you don't use the toilet when you stop in? Paper products in the bathroom are a cost, and those costs are put into the price everyone pays for a donut.
Now, I'll agree having a minimum plus percentage of every transaction is predatory.
Ultimately, my point is (not even addressing the legality of Visa's compulsory pricing attempts) the cost of upfront analysis to set pricing appropriately is easily dwarfed by the cost of labor and throughput when adjusting the price by employees at the point of sale. Maybe the merchants adjusting at sale are getting a benefit in the form of customer awareness, but I have doubts.