Store brands for stuff like bread, etc. are not only bought from the same manufacturers as the "real stuff", they show up on the same trucks and are faced by the employees of the same distributor.
Just because something is made by the same manufacturer at the same location, doesn't mean that the manufacturer used the same inputs/recipes in everything it produces. It can easily have different lines that use different quality levels of input at different price points.
I felt the implication of your original comment was "store brands are functionally the same as name brands", and wanted to clarify that was not necessarily the case. Apologies if I misunderstood.
