The rules are universal, only the mnemonics used to remember the rules are different

The rules and the acronyms describe different things. If you have to make more rules to say M and D are the same, and that you go left to right when you do them, then the basic rules you followed were flawed. The universal conventions of mathematics don’t need these acronyms confusing people.

high school Maths textbooks

I haven’t seen anything since early elementary school, not middle school, and certainly not high school. Regardless, if a textbook has it, it doesn’t make it right at all. If the acronyms are useless to learn, having them in a textbook doesn’t validate them.

and order of operations worksheet generators

…that’s one of the two examples you used? Did you think about that before you typed it out?

It’s always 2. #MathsIsNeverAmbiguous

IT IS AMBIGUOUS IN THIS POST AND ALL EXAMPLES I HAVE SHOWN. That is the problem at hand.

There is no real problem solving in trying to decipher poorly written shit. It’s the equivalent if English classes took time out to give students worksheets with “foder” written on them, and expecting students to find out if the writer meant “folder” or “fodder”- no sentence context, just following a list of “rules”. It is not difficult to write mathematical expressions with clear context to how numbers relate, even with the lazy shortcuts and shorthand that mathematicians love.