Unavailable executable still remains

Please note: This is not a question related to pip or python. I am trying to make sense of why I see a "permission error" instead of "path not found" error. I have done many installations and uninstallation for different softwares including python. So I can't recall how the setup was many years back. My core question is why I see an "zsh: permission denied: pip" instead of "pip not found". When an executable doesn't exist, I would expect it to be say "not found" vs pointing to a possible permission issue. And secondly; is there a way in linux\unix\mac to identify all commands\symlinks\aliases that are broken now? Here is my terminal output ayusman :$ pip zsh: permission denied: pip ayusman :$ which pip pip not found ayusman :$ type pip pip not found ayusman :$ Thank you.