Maybe it's because everything about the scene is so different compared to today's typical grocery store. There isn't a single environmentally unfriendly plastic bag to be found. The customer is writing a check. There are hanging plants (ferns?) above each check-out station, and the cashier is wearing what appears to be platform shoes or sandals. Not to mention that styling interior decorating combo that was so prevalent in the 1960s and 70s: bright orange and fake wood paneling. Who knew that running out for milk and bread could be so groovy?