Unfortunately, many patients do not understand the issues regarding store closing. I cannot speak for other states, but in New York, however a pharmacy cannot be open without a pharmacist legally. With this being noted, I am sure that most people understand that things come up (I.E. illness, death in family). Often it is not feasible to find a replacement, especially on a weekend. I am sure everyone has had to take a day off for some reason, is it not reasonable for a pharmacist to need the same.
To be fair to the nature of your concern, as compared to pharmacists, a pharmacist is a highly educated professional. They take time to work convenient hours for patients. Unlike many doctors, pharmacists are almost always available on weekends, late hours, and holidays. The point being is, a pharmacist has already bent over backwards to work hours most convenient for you, the patient, much more so the other private health care workers.
A pharmacy being closed should never be a big deal if you understand a few basic concepts. While inconvenient, an acute medicine can always be filled at another pharmacy, thus not causing a medical emergency. Furthermore, refills should not be an issue, as it would be irresponsible to order a medicine and pick it up last minute when it was needed. If planned at least a day or two in advance, if the store was closed, you could always come back another day.