Humans don't like the feeling of uncertainty in really any situation - and if there is any involved we desire for the tension of it to be resolved or avoided in someway.

Brands in a lot of ways offer humans this shorthand of lowering the level of uncertainty that they experience in their life.

When you are in an unfamiliar place in the world, and you maybe question the quality of food around you - you will in most situations prefer to go to a place like McDonald's - not necessarily because its the best food you could experience or even that it is the most cost effective option, but because it is the choice easily available with the lowest variance. That if you eat at a trusted brand like McDonald's you have a much lower probability of getting sick.

What you find when you study evolutionary psychology is that humans often don't seek to optimize decisions for average outcomes, rather optimize decisions that will reduce variance or in other words: uncertainty.