If you have to ask. I know it's a trite answer, but if you don't understand it, I don't think you can.
I have never once ignored a store's request to wear a mask. I was wearing masks before most people were, in fact, out of any (futile) hope it might help prevent me from catching the bug verses transmitting it, because I'm the primary carer for an at-risk family member.
When you tell me I must under threat of punishment? You better be able to make a better case for it than they've been able to make. Particularly when the actual legal framework used to try to enforce it is suspect, and has now been repeatedly challenged.