Not just overtime, it also means you worked full-time hours. Many of these retail stores intentionally keep people below 40 hours so that they never have to consider giving them benefits.

Back in my retail days, I worked exactly 39 hours per week, every week. If I was approaching 40, a manager would tell me to clock out and go home, regardless of whether or not I was needed.

That'll be hard to do once they complete their grocery monopoly.