>>12207030American uni takes 4 years because they leave high school with a single, unaccredited, AS-level equivalent qualification, and so get in based on how much of their free time they devoted to random "extracurricular" shit, and because they devote a quarter of even a hard science degree to the arts. They're treated like babies who don't know what to do with their lives, so they aren't even allowed to specialise. Imagine having to take all your GCSE classes until you were 19, that's America. Oh, and they have a national obsession with multiple choice. College-level literature class? 30% of your grade is multiple-choice "quizzes" on basic comprehension facts from the book. Want to go into postgrad? Better take a multiple-choice test to get a grade that matters to admissions departments, since they don't have honours degree classifications.
Americans reading this, you're going to get fucked to Hell and back in college if you want to actually study the subject you're getting a degree in. If you don't fancy spending tens of thousands a year to be told how you're literally the devil, apply to British universities: it's only £20 for a UCAS application to 5 unis. You won't regret it.