I think having the shop staffed isn’t necessarily a problem or failure. The original Go store in Seattle has alcohol (ID is checked by a person that permits entry into that section) and the store is otherwise staffed for restocking and general customer service. But I walk in, grab what I want for lunch, and walk out. I don’t wait in line behind 5 other people while waiting for the awkward chip card delay or that guy that wants to pay with pocket change that hogs the register. Consequently, I go there far more often than the 7-11 down the street.