Oh. When you got so upset as to use capital letters in your statement, I thought you might have known what you were talking about.
Obviously not.
Well to answer your question; why not?
Because the world of photography doesn't revolve around America, like maybe it used to back in the days of film.
Today, ASA, the American Standards Association 'system' still refers to the amount of sensitivity film has to light.
It was when digital started to rear its convenient head, it was realised ASA wasn't going to have the range to cope with sensors that would eventually be a lot more sensitive to light than film.
That's when the International Organisation for Standards got involved and ISO was born.
25 ASA to maybe 800 ASA and today we already have sensors with sensitivity north of 13000 ISO.
To all intents and purposes ISO and ASA are the same, but there is a slight difference. I won't go into that aspect here as I cant actually remember what the diff is and it doesn't really matter.

Hope that answers your question CPO.
Cheers

Really, my book advises the ISO standard for photography was established in 1974.
Wasn't that about the same time that a digital camera was first sold?
By the way, its ISO 'was' used, not 'were' used.

Edit
Here ya go from Google:
The ISO standard was created in 1974 by combining previous camera standards ASA and DIN. Here we will discuss how this camera standard is important for photography and how users can adjust the same to get better photos.21 Feb 2022

Why has this become such a contentious subject, with so much silly misinformation coming to the fore from people with limited knowledge but just want to be heard?
Becoming more and more prevalent on UHH.
I'm tired of the notifications and am unwatching this. Have fun.