Also like in Medicine, the US publishers charge US students much more than they charge students elsewhere (even in other Western countries). I think part of the

Also like in Medicine, the US publishers charge US students much more than they charge students elsewhere (even in other Western countries). I think part of the reason they're able to do this is because college itself costs much more here. When people started importing international books, they started changing the questions in those books. That's also how they are able to sell new editions constantly. Many subjects (math, mechanics, etc.) don't change much, but the publishers come out with different editions every 2-3 years so people can't just buy used books. It's a ridiculous system, but hopefully open textbooks and online education will help change things.