it most likely is this, just a particular store where an employee or maybe a manager cares enough to put this effort, by no means a company-wide improvement in this regard
It's definitely a case by case basis. The petsmart by my parents house in Maryland is garbage, i'd NEVER buy anything from them, however in Greensboro, the Petsmart here has some knowledgeable employees and I've heard them refusing to sell cichlids and bigger fish on a few occasions. Also saw them stop a lady from buying two male bettas for a fish bowl. It's all about the management and who works at that particular store.