Independent grocers can potentially compete. There’s a great one in my small town, and I had lots of options when I lived in Toronto.
Costco treats their employees and customers pretty well (but I’ve heard they’re not amazing to their suppliers since they push returns costs onto them?)
It’s not as convenient, and not quite as cheap, but I could pretty easily exclusively shop at Costco and a few small independent stores. My wife and I already joined the boycott bandwagon. We’re not using our PCF MC this month, either.