The SNAP rules don't require equal treatment with people who pay with credit cards, debit cards, or checks, only with people who pay cash. Setting aside the politicized USDA public communications during the shutdown, here's the legally binding regulatory text:
"Coupons shall be accepted for eligible foods at the same prices and on the same terms and conditions applicable to cash purchases of the same foods at the same store except that tax shall not be charged on eligible foods purchased with coupons."
https://www.ecfr.gov/current/title-7/subtitle-B/chapter-II/s...
"Coupons shall be accepted for eligible foods at the same prices and on the same terms and conditions applicable to cash purchases of the same foods at the same store except that tax shall not be charged on eligible foods purchased with coupons."