I see it as a yin-yang situation. Corporations are a way to organize capital for the benefit of the capital owners, unions are a way to organize labor for the benefit of the labor "owners." In a healthy capitalist system, both are necessary in order to maintain balance.
That's the ideal. In the real world, both types of organizations will seek ways to exploit any advantage in their favor. But that's life.
Corporations and labor unions are not really equivalent.
If you view them purely from the point of view of market power, then yes, they are the same thing. Both create an oligopoly in the market for buying/selling labor.
But corporations also are the way that both capital and labor are organized to produce an actual product. There is no analogous role for unions, except some special unions that play a large role in management.
I'm not sure what you mean by "livable working conditions"
If you are referring to total compensation and hours, this comes under what I referred to as "oligopoly". That is, labor unions can create market power on the side of labor, in order to raise pay.
However, this doesn't benefit society as a whole, and so it is only reasonable when there is market power on the other side. In my industry, there did seem to be an attempt to form a cartel of employer, but Mark Zuckerberg seems to have broken that cartel.
If you are referring to actual working conditions, like workplace safety, I already mentioned that when I talked about special unions that are involved with management. E.g. in very dangerous professions, unions might be part of the "deal" where management and workers agree on how to, as you say, organize labor and capital.
In general, however, and especially in IT, there is no need for unions because the market for labor is competitive, and working conditions can be negotiated between the worker and the corporation.
I agree IT unions aren't very necessary. We have it easy; we're well paid, we're fairly flexible, and if one employer sucks, we can easily can a better job elsewhere.
But plenty of industries don't have that advantage. Many workers are very dependent on a single employer. This is especially the case with workers that have highly specific training and experience that doesn't translate well to other jobs. If they're exploited or otherwise unhappy, they can't simply quit and get a similar job elsewhere, whereas the employer can afford to lose a single employee and train a new one, which makes the employer-employee relationship an unequal one. There, unions can provide a lot of value to keep employers honest.
That's the ideal. In the real world, both types of organizations will seek ways to exploit any advantage in their favor. But that's life.