The problem of course is when position is actually important in a problem, you need to integrate velocities instead of rapidity. The reason velocity addition tr

The problem of course is when position is actually important in a problem, you need to integrate velocities instead of rapidity. The reason velocity addition trips people up is because adding velocities inherently means "seeing velocity as measured by another frame," which then requires Lorentz transform. For many problems, you confine yourself to a single inertial frame, you can still do physics comfortably and you never have to worry about adding velocities.