Earlier quoted context omitted.
I mean look I have to sympathise with Google here. They've no doubt had the entire combined wisdom of Google looking at this problem and clearly there is just no way for human beings to comprehend what the `Accept-Language` header does. /s because, you know.
Except, in non English speaking counties, the vast majority of people do not change the Accept-Language header (through various browser/OS mechanisms), and receive default results. But then experiments show that they are more likely to interact with pages when shown in the languages Google thinks you actually use. If you go to myaccount.google.com/language , you can remove languages you don't actually speak, or turn…
I live in a non-English speaking country.
The vast majority of people use their device in the local language, and for any browser to see the OS is set to - let's say, Thai - and then just proceed to send accept-language: en is just absurd.
The other possibility is that these people who can not understand English, somehow manage to use a device set to English language on a daily basis. Also, absurd.