Security and convenience are diametrically opposed and stores are specifically built around convenience. I’m not sure it’s obvious at all what the right cutoff level is.
One store loosing its frozen food is an inconvenience and insurance claim, and one electric substation failing is an inconvenience for a few days.
But whenever any one of these attacks could be scaled up, as is obviously possible with online access enabled, and the consequences become a regionally or national security threat, enabling such access must come with the seriousness of implementing national security.
Unfortunately, it is not sexy for politicians to take national security seriously, and they will get inundated with lobbying decrying the costs. Until the losses to the companies exceed the costs of security, when they come screaming to the govt for help, and demanding why they didn't do something.
It is the same with almost every systemic problem that seems small now but is cumulative and/or exponential.
And for sure, if it is a few stores, it is just an expensive prank. But scale it to the size of a nation or region in a country with a largely just-in-time food supply, and you're a week away from food riots, particularly if it is combined with other attacks, e.g., on the electrical and distribution system. Not a shot fired, and the country is in chaos in a week. Because no one bothered to harden the systems that seem trivial but are critical at scale.