All the more reason people would prefer to work for a co-op, no? I really don't know why there aren't more co-ops, and am inferring they just don't work all that well. But if there are any regulations or something preventing them from succeeding, I'd love to know about it.
Also, I guess it's worth noting I've been "exempt" all my life (not subject to 40 hours a week), so that particular labor win I guess didn't really cross my mind.
If everyone has 40 hours a week + overtime and you have a coop that pays competitively for 24 hours a week and no overtime you won't get as much market share, can be outcompeted. It has to be done on a large scale, historically as a matter of policy. This was true for tons of different reductions in the workday and other labor rights improvements in the past.
Co-ops face a massive financing struggle, as most money is owned by rich investors, not by working people. Imagine running a business that can basically only get money from bank loans.
In a much more equal society this would go away to a great extent, but we don't live in anything close to that. So, if any co-op finds some useful niche, it will easily be out-competed by some company taking billionaire investors. The only exceptions are fundamentally limited businesses, where billionaires don't care to invest to outcompete, or the rare situations where it happened to not go that way before the co-op grew large enough, such as Mondragon in Spain's Basque Country.
Beyond this, there is of course the problem of the chicken and the egg. There are vanishingly few co-ops, so there are very very few people who know how to successfully lead and manage a co-op. So, many co-ops will face internal organizational issues and fail, as often happens with any other type of org run by people with little experience. But this then perpetuates the cycle. The same thing happened in the regular business world - many historically common organizational practices seem absurdly bad from today's standards, but they took time to be understood and repaired.
And finally, especially in B2B scenarios, there are real biases that the corporate owner class has against this type of organization, both personal and structural. Lots of B2B deals are built on interpersonal relationships between the owners and executives of these companies, a world in which the elected leader of a worker's co-op would not have the financial means to participate, even if the deep classism of the corporate elite wouldn't keep them out either way.
Also, I guess it's worth noting I've been "exempt" all my life (not subject to 40 hours a week), so that particular labor win I guess didn't really cross my mind.