both coops and unionized companies operate within a capitalist structure and on the market (usually). Neither model can emancipate itself from its context. So I’m not sure about what aspect you expect to be different. And coops can be run with good governance where power structures are explicit, managed and democratically altered to reflect the values of the members. The case where you have few people controlling everything is a dysfunction, it’s not part of the model (and also can happen with unions).