I see, you have
no evidence for sweeping claims of "Billions and Billions". You only have some 'just-so' stories and intuitions. But in each of your cases, a person checking compensation at just a few non-cartel places would do just fine.
So, if the cartel employees and their friends in your conversations stay slightly-drunk/stupid/lazy, they'll keep working at rates lower than are available to them. Meanwhile, anyone shopping around gets paid a competitive rate, unaffected by the non-poaching agreements.
I can believe there's some localized harm there, especially for long-tenured people at the cartel companies, but any damage is self-limiting. It's not massive on an "entire greater Bay area technology job sector" basis.
Also note, these cartel companies were also constantly hiring from non-cartel sources, and there was no coordinated "cap" or "ceiling" on such offers. They had to win such employees in unrestricted competition versus both cartel and non-cartel companies – and they often did!
Since employees talk (as in your examples), even long-tenured in-cartel employees would then get info about fully competitive compensation offers, and up their expectations for the next compensation-review. So again, any damage from non-poaching collusion faces practical checks on its magnitude.
If you're an Apple/Google/etc employee who wishes you'd been cross-recruited with a big compensation offer, you have a right to be angry. (But, you're still probably not that angry, given how well things have been going for top employees at those places in the relevant era!)
But if you've been employed elsewhere, your anger is misplaced. The non-poaching agreements didn't hurt you... and maybe even helped for the reasons I gave above.