Oh, that's a good point. I've often thought that the reason unions are so important is that employers bargain collectively by default because, well, companies are groups of people, not individuals.

On the other hand, IIRC studies show that larger companies pay more than smaller ones, and I think there have even been suggestions that this explains some of the GDP per capita differences between developed nations, that some have more large companies that are then more productive due to economies of scale and specialization.