I think this is a very keen observation, and quite right.
The key context for open when it was being attributed as a core value was references from the Open Source Software world where a lot of early coworking folks came from. Open Source software culture is informed by ideas and ideals that, frankly, subvert a lot of the transactional nature of business. In this context, openness leans more towards a kind of generosity that doesn't always show up in business or business cultures.
I recently listened to a keynote about these themes that reminded me...I hadn't really heard these themes clearly articulated in a while. Don't be scared off by the fact that the keynote is from a software conference, the keynote is not technical in any way but more of a commentary on culture, business, and the complex value of "open" as it was intended to describe coworking.
https://rework.fm/open-source-beyond-the-market/
In my opinion, accessibility has a lot more meaning today than it did when it was first used to describe coworking. Early on, I think it was simply about the removal of visible gatekeepers. Again, remember, many coworking pioneers were corporate outcasts of sorts. Accessibility was, in many ways, about who you were (or were not) actively trying to keep out. So in those early days, it was more about eschewing credentials and applications in favor of "if you show up, you're welcome."
In hindsight, though, I don't think it accessibility as a coworking core value really addressed the subtle, less visible gatekeepers of power and privilege. The door was open, but we didn't always do a good job of proactively inviting folks who weren't showing up or asking why they weren't showing up in the first place. I'm personally guilty of this, and have done a lot of work personally and organizationally to
take a much more proactive stance on accessibility.
I hope this helps! I think having core values that are open to some interpretation is why they're not "core rules." Asking what they actually mean, and how the meaning has changed over time, is part of why they're valuable.
-Alex