Unions, The Principal-Agent Problem, and Luddism
In response to Karen De Coster's objection to unions on the grounds that organized labor tends towards Luddism, Charles Johnson rightly points out that this problem is merely a function of the larger principal-agent problem. If I just get paid an hourly wage while my employer owns the firm and reaps all the profits, I will tend to actively oppose any technological or efficiency improvements that increase productivity on the grounds that doing so will reduce the labor hours needed and thus the amount I'll get paid.
Charles argues that this needn't be so; the principal-agent relationship need not be set up this way. Alternative arrangements, such as where labor collectively owns the means of production, through a co-op, for example, are also possible and in many ways more desirable.
However, it's not so clear to me the principal-agent problem is as easy to solve as Charles suggests it is. And it becomes even more difficult the lower down you get on the food chain, where labor is less-skilled, less-educated, and lower paid, and where labor may therefore be more averse to risk than otherwise. After all, one of the myriad justifications for profits going to the capitalist is that the capitalist takes on the most risks, using her own money as an entrepreneur to start an uncertain business, with a high failure rate, and also extending in time when she will get recompensated, assuming the business becomes successful. Whereas a poor laborer just scratching by may not have the wherewithal to take such a large risk, nor be willing or able to withhold present consumption for the chance at a bigger future payoff - the poor laborer just wants a certain payoff now, in the form of wages.
Now, one can certainly imagine a group of people getting together, pooling their resources, and collectively engaging in entrepreneurship, with the plan that they will all work together as laborers in the firm, share the profits, and also share the risk of loss. Instead of starting a new firm, existing workers within a firm might even pool their resources and collectively buyout the assets of the firm from the existing capitalist owners. Or, organized labor could just demand some compensation in the form of stock options or other claims on portions of future profit. And we already see some of these models in existence.
But becoming an investor and a risk-taker generally presupposes some level of acquired wealth, where you have taken care of basic needs and have some money left over to risk and save. Poor laborers aren't generally going to have access to that sort of capital, and they are the ones who seem to benefit from organizing their labor the most.