what's the default/defacto scripting language on all unix or unix-like operating systems?
Bash. (except MacOS I guess)
why? because it is the best thing that everyone can agree on as being the stock shell that should always be installed by default.
until we collectively agree on a replacement, bash will remain, along with all of its problems and everyone will write for it because it's the standard shell that's always installed.
many much better shells exist. we can't agree on what should supplant bash, and so it remains. everywhere.
I fear there will be no defacto bash replacement for many years.