The different stores as well as the different states are doing things differently.
The smaller Joann just a mile or so from me remained open as an essential business this entire time, the requirements/restrictions to enter have varied. The larger store at the shopping mall was closed to customers and was for outdoor pick-up only.
While it is an inconvenience to us as the buying public, the sales clerks also need the protection from interacting with many people over the day (not just "us"), even if they have some degree of protection -- separation is the best form of prevention we currenty have.