There still is a semi-democratic process (barring large-scale network effects for the sake of discussion): whether a given person chooses to become (or stay) a customer. People vote for or against a company’s products/services with their money.
Co-ops are usually a republic, not a democracy. People still have specific roles, and those roles have authority to make specific decisions without getting a majority vote for that decision.
I don't know enough about co-ops but it seems to me they not only redefine the power structure, they also redefine what success (for themselves) is and the means to reach it. Unfortunately ou can't directly compare the two.
