I observe something similar when talking to small restaurant owners in the town where I live. They are often severely challenged by aspects of running a business that they never really anticipated or planned for, including the costs of accepting card payments. They can typically tell you what they paid (or pay on a recurring basis) to get a POS terminal, and what percentage of card sales is creamed off by their processor, but that's all. They are often not aware that they might be able to get a better deal with a different processor (if they're prepared to swallow termination fees and buy/rent a new terminal). They are even less likely to be aware that their 'choice' of processor might make a difference to some of their customers.
Slightly OT, but having seen how sketchy some of the salespeople who work for the acquirers are, I totally get why products like Square are extremely popular. Sure, they don't provide the best rates (especially if most of the cards you see are debit cards), but their pricing is easy to understand and the hardware/software is straightforward as well. You also don't get locked into a long-term contract if you decide another card acceptance product works better for your business.
Unfortunately those are a lot less commonly offered outside the US, so foreign merchants are generally stuck with whatever their bank offers. Even if that means DCC is enabled by default and not easily bypassed.