The average person doesn't consider them to be a viable option. Don't ask me why, but it's true. And them being considered a viable option is a prerequisite to competition working right.

The average person (at least in the US) does not consider the world’s largest retailer, with a well known reputation for being the cheapest, an option? I don’t buy that.

That WalMart link is to decorative glasses, not prescription glasses.

So here's the thing with WalMart and Luxottica - their insurance does not fully cover WalMart! They give you a significantly reduced amount with WalMart (or Costco), that's how you know it's fraudulent - they only want to cover their own stores, that's not a normal behavior for "insurance".

Perhaps these are better sources.

https://www.cleverdude.com/content/costco-optical-vs-walmart...

https://clark.com/health-health-care/costco-optical-eyeglass...