As I recall, this statement was specifically about Apple Intelligence. It was for their AI that couldn’t be done on-device, and wasn’t going to ChatGPT after user authorization.
It was not a general statement that all Apple endpoints are in-house.
And what’s the alternative? Google? Their business model is based on collecting and using user data to increase profits in their AdWords business.
As far as I can tell, the article being discussed made up the ‘fact’ that Apple made such a claim.
I googled the ‘quote’ from the article This raises questions about Apple’s public privacy claim that such system data “never leaves Apple servers or goes to third parties.” and could not find any evidence that Apple actually made that claim. Even the phrase “leaves Apple servers” doesn’t get any hits to statements by Apple.
I also browsed https://www.apple.com/privacy but couldn’t find anything there that’s close to that statement.
The closest I found is a statement about Private Cloud Compute, where they say “If it requires greater computational capacity, it can draw on Private Cloud Compute and send only the data relevant to your task to be processed on Apple silicon–based servers” (https://www.apple.com/privacy/features/)
So, even there they do not claim they own those servers or that they are located in Apple’s data centers, but I think it can be inferred that they own them.