alt Hacker NewsLots of people say lots of things. I don't see why Adam Smith is special. Price fixing can work within reason.
Did you know that the communism-themed Fusion Festival fixes the price of a meal, across all 100+ vendors, currently at 7€? This is presumably negotiated between the festival organisers and the food vendors as a reasonable price. (Some of them make a point of advertising 6.50€ but that doesn't actually make a difference. If you like the food you would've bought it for 7€ and if you don't like the food you aren't going to change your mind over 0.50€. They're just throwing away money.)(Some stands that sell more "snacky" items like crepes or smoothies use lower prices.)
Because the price is the same everywhere you don't have to comparison-shop and can just pick the food you like.
What is a meal though? Do you get the same volume of food from all vendors, and the same number of calories? I definitely order multiple items from restaurants that have small portion sizes, so I suspect some vendors would be better or worse deals even at a uniform price.