I can't think of a single reason to use bash over Python. Anything you can do in bash can be done in pure Python. Unless you're working in some embedded environment it's a non-issue to install a Python interpreter (you certainly already have one). I would only use sh/bash for packages I'm distributing to avoid the external dependency, and then only if it's a relatively simple script.
Python is superior for string anything (parsing, searching, manipulating). But Bash is much simpler for running existing CLI tools. Plus you should already be using Bash as a simple terminal language already, so wrapping what you're used to into a simple script flows naturally.
Eg, if I have some admin tool for updating a user thingamajig, a common scripting need is just running that tool for every user in a file (or the output of another command). The string manipulation that often requires is annoying in bash, but running the commands is easier than Python.
If what you're doing is essentially a few shell commands, then you may as well put it into a script. If you're talking about how "elegant" your shell scripts are and comparing them to Python, you're probably wrong and should be using Python.