It's not the information in the chapters that changes, it's the problems that students do for assignments that change. For example a problem where one train is going 105 mph and another is going 90 mph gets swapped for one where one plane is going 605 mph and another is going 590. Conceptually it's the same, but obviously a student doing the one problem is going to get a radically different answer from the one doing the other.
And while calculus might have some public domain works that are acceptable, most fields have advanced pretty far since 1925, which might I remind you was before the discovery of DNA, penicillin, plate tectonics, molecular orbital theory, the neutron, the invention of digital electronics, Keynesian economics, Hemingway's first novel, etc.
And while calculus might have some public domain works that are acceptable, most fields have advanced pretty far since 1925, which might I remind you was before the discovery of DNA, penicillin, plate tectonics, molecular orbital theory, the neutron, the invention of digital electronics, Keynesian economics, Hemingway's first novel, etc.