I think it all comes down to how effectively branding and marketing have destroyed the EMH. Airplane tickets are fungible they're easy to compare on price. They're also expensive enough that people take the time to shop around. However because of the regulators no brand of airline is unsafe.

Buying an expensive branded cereal is probably not a completely rational action IF you could identify equally good no-brand cereals you'd save money. But certainly in the west the cost is such a small part of most peoples spending that they don't bother.