I understand that in many cases, merchants would put surcharges on credit card purchases, or offer cash discounts, in order to pay for transaction fees charged by Visa, etc.
However, a restaurant I go to rather often recently started offering a very high cash discount: 15%. As far as I know, not even the most reward-laden credit card would charge so much to the merchant, and besides Interac debit cards (which most people use) have very small transaction fees.
Why would such a large discount make business sense to the restaurant? Are there other costs related to processing plastic payment cards? Or can I assume that the restaurant is trying to avoid leaving a paper trail so that they could avoid paying tax?
Even if that's the case, it seems like one would have to hide basically all the cash transactions in order to break even with such a big discount, and that'll be very suspicious.