Comment by zorked

Kinda? Historically there were indeed concerns about reimplementation and copyright. One of the ways that the GNU Project tried to fight claims was to reimplement the tools using dynamically-allocated memory (instead of Unix's traditional fixed-size buffers) to make sure the implementation was sufficiently different. Other ways were making the implementation Posixly correct, adding internationalization or trying to pick different approaches (like using more modern algorithms for sorting). The GNU tools were better, not just direct ports, and that's why it was common to install them in systems like Solaris or HP-UX.