Where do you live? My experience comes from wealthy suburbs in Los Angeles and Miami as well as the Bay Area in general but different markets are different.

There can be many effects in play like marketing, staffing, and real estate prices. The Vons I mentioned is actually getting more expensive while the Pavilions is getting cheaper because the Vons cut back on cashiers. The longer lines have caused many of my friends and I to start shopping at Pavilions, which is causing a death spiral as Vons tries to charge more for produce just so they can pay the overhead on the building (the Vons location costs twice as much in rent as the Pavilions because of lease terms and the outdoor mall it's in, despite being across the street).