While I was never able to take advantage of this loophole (all my Safeways were strict on CASH ONLY,) but I had heard murmurs that if you got a willing cashier, you could swipe a cc instead of a debit. This lasted for quite a long time too.
Anyhow, I gave it a shot not too long ago (using Apple Pay,) and the cashier looked confused at the screen. She then called in a coworker who shrugged her head and pushed probably the “okay” button on the screen. The cc reader then showed that the payment only took off the MO fees, so there goes that. It seems the system is now hard-coded against letting you use a cc to buy a MO (heard it died in June of 2019 or so.) Kudos to all who hit this hard over the years.