And those countries are wrong. Using a comma as a decimal point makes no logical sense, especially in computing. And it's ugly from an aesthetics standpoint.
I think what plays into this is also language. In English / to you, I presume it makes perfect sense to say "Pi is approximately three point one four".
In other languages (for me, German) the literal translation "Pi ist ungefähr drei Punkt eins vier" sounds awful and wrong. We say "Pi ist ungefähr drei Komma eins vier" ("Pi is approximately three comma one four") so we also write it like this 🤷🏼♀️
It sounds wrong to you because you grew up saying it another way.
There is no one way that objectively makes more sense than the other, each language simply has its own habits. If everyone in Germany said "drei Punkt eins vier", it wouldn't sound awful to you at all.
Sure, but if everyone said it differently, than that would also be part of the language. I don't disagree with you, I just think you've described language (in this context) 😄
Also, both systems make equally as much - or little - sense. Math notations is just using whichever symbol is commonly available and easy to write without asking whether it makes logical sense.
Are you complaining that the factorial operator makes no logical sense either? Or the "#" symbol for the cardinality of a set?