Why do people think companies act rationally? Behavioral economics shows time and time again people make irrational decisions all the time. Considering company

Why do people think companies act rationally? Behavioral economics shows time and time again people make irrational decisions all the time. Considering company is just a group of people, these irrational decisions are compounded. So I wouldn't say it's 100% clear whether a company saves money retaining employees vs training new.