Coop is a brand. As just two brands (Coop and Migros) monopolize (or rather
duopolize) much of the retail business in Switzerland, you easily get the impression Coop or Migros were just normal words. Not very consumer-friendly.
Well, yes, but no one ever said a "convenience store" had to be consumer-friendly. I would call both a Shell station (so similar to Coop)
and a local mom-and-pop store (so Tante-Emma-Laden) "
convenience stores," insofar as they both are small but at the same time carry all the basic essentials that one would need in a store (so a fine gamut of things), despite the fact that perhaps the mom-and-pop store may be friendlier/warmer and the Shell station colder/more commercialized/less consumer-friendly.
Or did you mean that "Coop" and "Migros" are actually used as "normal words" to refer to a convenience-store type place? Kind of like the old kleenex = tissue paper situation.