In my experience, those kinds of shell scripts get written by people who needed automate something quickly and didn't have (or at least perceive) any other lang

In my experience, those kinds of shell scripts get written by people who needed automate something quickly and didn't have (or at least perceive) any other language available besides maybe Perl. They're either Unix admins without much programming experience or they're part-time programmers who primarily work in some other language and just don't have the familiarity with Python or Ruby needed to write a good glue script. But they know how to accomplish this task interactively in the shell, so scripting what they're already doing (or already know how to do) seems like the natural next step. So you wind up with an imperative shell script that's basically a long, flat sequence of commands with some logic and variables sprinkled in haphazardly as they realized they needed it. Due to the organic way these scripts often emerge, it's not like advocating Python is an easy sell. By the time they think to consider alternatives, the shell version already exists.