There is a long history of alternative shells csh, tcsh, zsh, fish, etc. All with various level of abstraction and various amounts of "programming language type constructs" (for lack of a better term).

At the end of the day, long arguments have been had over which is the better shell. It's all just personal preference. Hence it can be set in /etc/passwd per user.

You prefer python? chsh is there to change it.