Debit card fees are capped in the US, yet I’ve never received a discount from a merchant for paying with debit instead of credit.
As such, I just pay with credit and have never understood this argument.
Managing cash for a merchant also brings real costs as well.
You have to take it to the bank or pay a service to pick up cash. You’re way more likely to have “leakage” when any cashier can pocket cash. Etc
Because the merchant pass the higher processing cost to all customers.
I know this because I used to work on a US military base. There was a sole merchant on a particular installation that was doing this, but it was extreme. They'd force you to buy over 10 USD if you wanted to use a card, and it was the only place to grab a snack. One day there terminal was shut down, and for a period they only went to cash payments. Once they took credit again they removed the minimum purchase. Turns out somebody got pissed, and reported them.
Regarding the article, the ~390 USR sounds about right to me. I only use a credit card, pay it completely off at the end of the month. I've never once paid interest since in the 8 years I have used this card. Every few years I buy a plan ticket with the rewards.
This also varies by country, but I think Visa/Mastercard relented on it in many jurisdictions.
In Australia, for example, merchants have been allowed to add on credit card fees everywhere, and their card readers automatically tack on the fee when they detect a credit card.
It used to be true, but this changed many years ago.