ladybusiness | Just by way of background to your points (Reply)

From:

In the case of cozy mysteries, I see key aspects as being that *things are generally fine.*
The government is just and humane. The economy is mostly going fine. You and your friends are okay and do not need to worry about your survival. You HAVE friends, a pleasantly-large circle of best friends and middling friends and neighbors with whom you are on good terms, and romantic happiness if the author is inclined that way. Life is generally pleasant. The only problem is the murder, and it's discrete and capable of being solved by the end of the book.

The details of how things are fine vary - cats, gardening, knitting circle, sudoku, home renovations, antiquing - but whichever details the author puts in are enjoyable ornaments to daily life, the kind of thing people CAN enjoy when they're not worried about whether they'll make rent.

I think this is one way 'cozy apocalypse' and similar veins can fail, as you point out. If it's only cozy for the viewpoint character, and outside the circle of warmth there is terrible suffering or oppression, that violates the 'big picture is generally fine' principle of coziness.