Python isn't suitable (by default) when the main task is to run multiple other programs, in pipes and elsewhere. Env vars are a bit harder to get to, etc. Common sys-admin use cases basically.

Yes, you can write a run() function that handles everything, and there are some 90% solutions in subprocess now, but the defaults are not as simple as a modern shell on this dimension.

Of course, if you need to do any string manipulation, advanced conditionals, or math, Python quickly pulls ahead.