There's a whole corner of the advertising world dedicated to straight-up fooling consumers. They study things like how a taller, thinner package is perceived to have a greater volume than a shorter, wider package that in fact holds the same amount of product. They then use that knowledge to give you less stuff for your money without you knowing.

One of the easiest places to attack free market fundamentalism is on the baseline assumption that real-world markets operate with something approximating perfect information. Not only is it far from the case that all participants have perfect information, but you have huge companies dedicating effort to fool ordinary consumers who don't have the time or energy to sift through all this shit.

It's called industrial-organizational psychology. Essentially applied psychology for anything that isnt mental health or academic research.