Do you remember the no poaching agreement started personally by Steve Jobs? They have been a cartel for decades. They share board members, they compete only as much as not to threaten the status quo.
Eric Schmidt was CEO of Google starting between 2001 (so 2 decades ago) until 2011 and Apple board member between 2006 and 2009. He wouldn't have gotten the position in 2006 of Google and Apple weren't cooperating.
I've been saying it for years, but I never thought I'd see either company say anything like that as boldly as they did. It's like something out of a cartoon.