They had intended the cartel to last for thirty years (1925 to 1955). The cartel ceased operations in 1939 owing to the outbreak of World War II.
So they didn't actually last all that long.
Both organisations co-ordinated the trading of patents and market penetration.
Patents are a government-granted monopoly.
> Neither cartel relied on regulatory capture
This is not remotely true for Apple and Google. The laws are written to allow them to exclude competitors. Why doesn't Amazon buy a bunch of iPhones and modify the software to include the Amazon App Store and then sell them to customers? Laws prohibit this.
And then it's the same situation again -- copyright too is a government-granted monopoly. Finding that a monopoly exists where the government prohibits anyone from competing with them was the original theory. Let's have 14 year copyrights again and see how the monopoly holds up when Apple has to compete with a fork of the original iPhone which would be out of copyright by now.
The Phoebus cartel[1] existed for quite some time, and its operation contradicts this argument. They captured the world-wide light bulb market with agreements between manufacturers. It took WWII to put a dent in it.
Today, you can look at the price fixing that happens in the mobile app store and payments markets. 99% of each market is dominated by a two company duopoly. Prices in those markets have remained steady for over a decade, and any changes to pricing and terms are adopted in lockstep between Google and Apple. They've effectively captured 15% to 30% of all revenue collected in mobile apps.
Neither cartel relied on regulatory capture, but both cartels recognized that without collusion, it would be a race to the bottom if they compete on price, so they became complicit in ensuring that doesn't happen. It only costs so much to make a light bulb, download an app or process payments.
[1] https://en.wikipedia.org/wiki/Phoebus_cartel