Proprietary, money driven development, is top down and has coordination in general. In very large software, it starts failing sometimes (I’m looking at you Oracle)
Open source handles conflict by forking. I wouldn’t call that good coordination.
But, at the same time, I don’t see a better (or less worse) solution so I shut up and I take their code =)
Forking is far from the first step in conflict resolution; it is the ultima ratio between projects in the open-source world, when all dialogue breaks down. In other words, the worst outcome is that people agree to disagree and go their separate ways, which is arguably as good a solution as is possible.
In the corporate world, coordination mostly exists within companies through top-down decision-making, as you said. Between them, however, things look much grimmer. Legal action is often taken lightly, and more often than not, a core business goal is to not just dominate, but to annihilate the competition by driving them out of business.
Coordination between corporations, such as through consortia, is only ever found if everyone involved stands to profit significantly and risks are low. And ironically, when it does happen, it often takes the form of shared development of an open-source project, to eliminate the perceived risk of being shafted.
You also do a fork if you simply want to try out some rather experimental changes. In the end, this fork can get merged into the mainstream version, stay independent, or become abandoned. People wanting to try out new things has barely anything to do with all dialogue breaking down.
The latter is where you need the coordination. In a company someone high up can say "we're doing it's like this" and everyone has to fall in line.
Thus far, open source has optimized for maximum utility for individuals who can write code... but AI may be changing that soon enough.