If they don't swoop in with random check-ins hassling you for docs for "muh KYC" and "muh AML compliance" the moment you do anything outside of the boring middle ground then they're ahead of basically 99+% of all the other tradfi-interlocking offerings.
It is what it is. You have to implement KYC if you want fiat rails. A merchant can't KYC every single person that comes to the store. But you could build a system to eventually ban wallets that could be tied to criminal activity.
The merchant can also pick to use Lightning and keep the Bitcoin instead of selling it for fiat.