No it doesn't prepare us for adult life, Your life in school prepared you in just the wrong way for your life at work. In early school, your classes are chosen for you, the class material is outlined by the government (of all things). In later schools, you have some say in which classes you take, and what sports or arts you’re involved in.
Then in college, a world a freedom! Of choice! You can pick all of your classes, pick your major, even invent a major! Study abroad, switch from economics to veterinary science just by filling out a form, play sports, start clubs, join a fraternity, take summer and winter classes. You’re in charge of everything!
Then you get a job, and suddenly, all of that freedom is gone. At work, you do what you are told to do, on someone else’s schedule, to someone else’s standards, regardless of whether you think it’s the right thing in the right way. You have just fallen from the pinnacle of being in control to the depths of being controlled.