I’m not sure how you could suggest starbucks and mcdonalds outcompete based on product quality or ambiance. Have you been to a random mom&pop coffee or burger spot recently?

Chairs aren’t magic, we know roughly what’s good or not. You don’t need a PhD to choose a good chair. A mom and pop could just copy the chair too.

The chains outcompete on marketing, leverage with vendors, etc.

They put a huge amount of effort into baseline quality because it’s incredibly hard to pull off across 1000s of stores staffed by people who don’t have any incentive to care.