Holy shit, that's it! That's why the individual always loses out in negotiating for their salary--the company is already one big team (HR, accounting, all the business processes, etc) and you're just some guy on the other side of the table.
Even for hot shots, a union would only be a benefit. Look at the Screen Actors Guild--hot shot actors bring in bank, they're not constrained by the union, but everyone involved gets the basic union protections.
Wow, that's it. Individuals always get defeated by the team, and that's exactly what it is when you go up against a company to negotiate your salary.