The small retailer I worked for didn’t take Discover. We took Amex though, because it was high-end and wealthy people love their Amex.

Editing to clarify, had to dash off before: wealthy people love their extra-thick Amex Black Card made of titanium or whatever, that we used to have to type in by hand because it would damage the old slide readers. So as long as we were taking those we took regular Amex cards too.