I don't think its that surprising. Bash is old as dirt and scripts by definition are meant to be simple. Where AI struggles is when you add complexity like object-oriented design. That's when the effect of it trying to solve every problem in a way unique to it just takes shit off the rails. LLMs known design patterns exist but they don't know how to use them because that's not how deep learning approaches problem solving.
FYI, you're missing two patterns that allow the `--key=value` admirers and the `-alltheshortopsinasinglestring` spacebar savers among us to be happy (for the otherwise excellent options parsing code).
shopt -s extglob
case "$1"
# Flag support - allow -xyz z-takes-params
-@(a|b|c)*) _flag=${1:1:1}; _rest=${1:2}; shift; set -- "-$_flag" "-$_rest" "$@";;
# Param=Value support
-?(-)*=*) _key=${1%%=*}; _value=${1#*=}; shift; set -- "${_key}" "$_value" "$@";;
esac
I got a couple bug reports years ago on https://github.com/jdavisclark/jsformat for not dealing unicode emojis correctly when used in variable names in javascript. people are weird.