I, as a private individual, can accept card payments for 1.69%. I have a physical chip and pin reader (that pairs with my phone), it cost me £25, but I can take contactless payments using just my phone. If I didn't want to use my phone, I'd need the £75 reader that comes with a 4G connection (at no extra transaction or subscription cost).

If I were charging £3k/month, I'd be just above the threshold where paying £19.99/month to get a transaction fee of 0.99% saves money overall.

I get the terminal directly from my bank here in Spain, it's something like €5/month + 0.02% of transaction. Is it much higher in other parts of the EU?

0.2% of 3000€ is 6€. I’m not sure how big of an impact that is, considering the non-negligible costs of handling this much money in cash. If a business earns more money after accepting cash, it’s probably because they don’t pay taxes.