The "dollar" stores used to have very good buys. But that was when they first started and were stocked with regular- and large-sized closeout items purchased from wholesale and retail grocers who were going out of business. For example, one could get a large bottle of expensive Kalamata Olives for a dollar. They had different items all the time, depending what their buyers could find in closeouts. Now suppliers are packing items in special, small packages and bottles designed to be sold only in dollar stores, resulting in the not very good buys you referenced.And the items available rarely change.
I see; I was never in them until the second phase (as they weren’t around yet in my area). Now we have a few of them in town, and they all sell the same things - like walking along the boardwalk on the Jersey shore...