How is that? I don't know about Chinese, but surely Japanese has much better entropy in bytes? As would other languages with more expressive character sets.

That's the issue. English can be represented with 7 bits. Good luck doing that for any logographic language.

And that doesn't even take into account that since English (and a lot of alphabet based languages) use spaces to mark where words begin and end. In Japanese, you can have a word that consists of a kanji plus a few hiragana characters as a grammatical marker. But there's no space between that word and the next. How do you know decide where to insert a line break?

It's not a coincidence, the A in ASCII stands for American.

Sure, but just the fact that roman characters with no accents (or just a few), plus all of the punctuation, fits in a 7 or 8 bit key space.

And even 5 bits was enough for a long time, across a few European languages: https://en.wikipedia.org/wiki/Baudot_code (which I just learned is also where "baud" comes from!)

Is it more convenient than any other phonetic script? I just happened that ASCII was based on English and became the standard.