Openness is a different concept from what I was discussing. Our kids didn't have any issue discussing with us how things were going in their academic pursuits, high school, college, whatever. It's somewhat the same with many other things, such as finances, budgeting, etc., although a lot of that perspective is in broader brushstrokes since we don't see the need to be privy to any nitty gritty details of bank balances, take home pay, retirement amounts, how much they spent on their vacation, etc.
They demonstrated an understanding of pursuing their education for their own goals, not ours, and we let them take the wheel. They decided on their career path, picked their school of choice and we sent them off because we knew they were responsible and they followed through without need for us monitoring their progress. Sure, they discussed with us what they were doing, how it was going, etc., We weren't disinterested. We simply didn't feel the need for any heightened vigilance.
Financial matters have kind of a similar trajectory. Trained them with the basic guardrails as they grew up and let them handle things for themselves as they aged and matured into the responsibilities. As they arrived at different phases of adulthood we gave them our best guidance and answer any questions they ask and trust them to handle it responsibly because that's who they've always demonstrated they are. I guess for me it's just, yep, those are my leopards, same spots they've always had, no documentation needed to tell me that.