Major retailers aren't giving up on '70s music. J.C. Penney's latest radio commercial features Redbone's "Come and Get Your Love" from 1973. And Walmart has a radio ad featuring Gary Numan's "Cars" from 1979 (although that's an honorary '80s song because it didn't reach its Billboard chart peak until 1980).
All of which is different from music played in stores et al.