How do the science and math papers use characters that aren't in... ASCII? Maybe I need to look at an ASCII chart.

Out of curiosity, isn't UTF implementation much easier now than it has been? I piddle in writing things and I rarely contemplate UTF. Once I tried to reverse engineer an encryption plugin that used Asiatic characters as the ciphertext, and I wanted to use emoji, and that was when I learned I am too dumb to understand utf. But there's libiconv, which I first saw in production (ICQ or aim or Trillian or so) over 22 years ago, personally.

So is the latex thing obstinance, technical, or political?

Your statement is not correct, LuaLaTeX can output any unicode character you need and also you can use Lua as well for scripting.