I'm not sure inertia is correct for this. I think the reason is there are no needs for non-english charactered programming languages. Let's think about there are perfect program language made with Korean. If you are programmer, then you already know program languages made with English even if you are not a native speaker. Now you have to learn "New" program languages. You are native Korean so maybe have some advantage but it is still new thing. If you are not programmer yet. You have to learn program language, in this case most users are already using traditional program languages so you can't skip Python or C or Java.

I think another part of it is culture. Outside of Western tech circles there's far less a culture (it feels) to invent new languages. To my knowledge Ruby's Matz is the only notable exception, and he's highly unusual as a Japanese. Then, using non-ascii-friendly character set is an even greater challenge.

Non-ascii encodings are harder to program in due to the need to switch in and out of input methods.

That said, some languages like Arabic and Japanese (and possibly Korean and Hindi) lend naturally to VSO token ordering, which maps directly to LISP syntax, so it's unfortunate that there isn't a lot of interest in this. It would be lots of fun. Maybe agents will make this possible!

Here are some interesting examples.

    - https://github.com/nasser/--- (Arabic)
    - https://honoka.nukenin.jp/Introduction/Loop.html (Japanese)
    - https://github.com/wenyan-lang/wenyan (Chinese, which is SVO like English)

Using english for your programming language gives you the widest audience.