[foldr]

Apple added /bin/dash in Catalina, and the intention is probably to eventually to use dash as the implementation of sh: https://scriptingosx.com/2020/06/about-bash-zsh-sh-and-dash-....

As for why they haven't done it yet, I'd guess it's just to preserve backward compatibility with old scripts that rely on quirks of bash's sh compatibility mode.

[lelandfe]

Oh they added it to recovery too. Interesting.