That's a valid point surely but it's not a simpler explanation. The simple explanation is that you will have your ability to accept credit cards pulled if they

That's a valid point surely but it's not a simpler explanation. The simple explanation is that you will have your ability to accept credit cards pulled if they find out you are charging more for CC purchases, although you are allowed to have a "cash discount" just as was stated. It's in every agreement. I'm a bit shocked that people are arguing about this actually, but I guess accepting credit cards and setting up card present accounts isn't exactly a universal experience. I'm not sure how/if this was recently changed in the US, my knowledge is 5+ years out of date now and I'm not in the US either.