As a business owner, there is also a monthly generic processing fee. Oftentimes there’s a software licensing fee. There’s also a compliance fee (sometimes). There are also periodic shore-up fees of the over/under was off during the month. Sometimes there are equipment rental fees or service fees, or you can buy it outright but there’s typically still a monthly fee to use it.
Also AmEx is the worst offender depending on your processor, they can charge upwards of 6% to process. Discover is around 3%. Visa & MC are ~1-2%. That’s why blended processors tend to be around 2-3%, but it also depends on volume.
Honestly, looking back at a former small business I had, I think it would have been better to be cash only and have an ATM. I know it’d annoy some customers, but our fees/costs just to accept cards was probably 5-10% of gross revenues each month. Then you take out labor, utilities, rent, raw cogs, etc. and your net margin gets real small, real fast.