Maybe if you're one of those AI behemots who works with exabytes of training data, it would make some sense to compress it down by less than 50% (since we're using lots of Latin terms and acronyms and punctuation marks which all fit in one byte in UTF-8).
On the web and in other kinds of daily text processing, one poorly compressed image or one JavaScript-heavy webshite obliterates all "savings" you would have had in that week by encoding text in something more efficient.
It's the same with databases. I've never seen anyone pick anything other than UTF-8 in the last 10 years at least, even though 99% of what we store there is in Cyrillic. I sometimes run into old databases, which are usually Oracle, that were set up in the 90s and never really upgraded. The data is in some weird encoding that you haven't heard of for decades, and it's always a pain to integrate with them.
I remember the days of codepages. Seeing broken text was the norm. Technically advanced users would quickly learn to guess the correct text encoding by the shapes of glyphs we would see when opening a file. Do not want.
The byte order mark has has no relation to code pages.
I don't think you know what you're talking about and I do not think further engagement with you is fruitful. Bye.
EDIT: okay since you edited your comment to add the part about Greek and cryllic after I responded, I'll respond to that too. Notice how I did not say "all European languages". Norwegian, Swedish, French, Danish, Spanish, German, English, Polish, Italian, and many other European languages have writing systems where typical texts are "mostly ASCII with a few special symbols and diacritics here and there". Yes, Greek and cryllic are exceptions. That does not invalidate my point.