Rmack898 beat me to it.......This is not a fallacy but a fact......Years ago, I had a good friend, who was working in the field, school me.....We went to the box store and picked up a Moen sink fixture off the shelf, then went and purchased the same item at the plumbing supply house. He then laid out all of the parts side by side on his workbench....While the fixture appears to be the same, the internal parts are not always the same. Plastic vs brass, plastic vs a different quality plastic, etc and so forth.........