Alcoholics can literally die if they don’t have access to alcohol. I know someone who went partially blind because they quit alcohol too quickly. So liquor stores are pretty essential.
One of the main reasons cannabis was legalised in many places to begin with was because of its medical benefits. Millions use it as a painkiller, antidepressant, antianxiety, etc. If people suddenly lost access to cannabis, there would be a spike in suicides. So dispensaries are pretty essential.
As for gun shops, many people require access to guns and ammo to feed themselves, as well as defend themselves, especially if they live in rural locations. So gun shops are pretty essential.
Ideally, all three should be using strict social distancing measures, limiting the number of people in the store at once, using and frequently changing gloves, etc. But shutting down altogether simply isn’t an option