American grocery has spent forty years consolidating.
Regional chains got bought. The buyers got bought. Names that anchored whole cities disappeared into holding companies, then into larger holding companies, then off the sign entirely.
If you are over sixty, you can probably name three grocery stores from your childhood that no longer exist.
So when a family chain in a competitive metro simply does not sell, decade after decade, that is not passivity.
It is an active decision, repeated many times, against significant financial pressure and probably against some very large offers.
The interesting question is not why anybody would sell. That part is obvious. The interesting question is what you get for refusing, and what it costs you.