Traveling families and busy 'essential workers' need food, gas, and basic necessities. Access to quick food (McDonalds in this case), gas stations, and convenience stores are just as vital as anything!
I hear what you are saying. Gas stations are vital transitively from the vital jobs that require gas, such as ambulance services. But I could still rank them as less vital than the services themselves, enabling me to at least close some gas stations. Fast food would be far down the list because it is predictable and trivial to plan around.
It can take some real planning to figure out how to deal with that first week.
How come it is illegal to keep them open during public holidays in much of Europe then? I find hospitals a tad more important.