`grep -P` kinda annoying. GNU has Perl-compatible regex, and BSD does not. You're reaching for `perl` or installing `ggrep` the moment you need a lookbehind.

Is it still shipping with that ancient bash, the awful Iterm and without a package manager? I haven't used OSX for a while.

The overwhelming majority of UNIX-like software isn't designed for BSD runtimes, to name one.