That's interesting, my company takes a different approach, if we don't go contract to hire in a year, we choose a new person to fill the role.

I wasn't mentioning it as a preclusion, more as a how the heck would they expect a tech union to work. The Screen Actors Guild (SAG) is an example of a union for contractors, but that's more nice role as the positions are very difficult to fill for and the roles often can't be reasonably replaced. Tech workers though, that pool is HUGE. If you had a tech union it would need to contain a significant portion of 8% (26,000,000) of the US population. It would seem they would lack the bargaining power as they're easily replicable. Perhaps if you were unionizing inside a single company that provided contractors you could destroy their workforce by all walking at once, but google doesn't need to fire these people, they can just terminate the contract with the company that provides them.

If the contractors were employees, there would be a massive lawsuit incoming (may be anyway) as the National Labor Relations Act (NLRA) protects the rights of employees to organize and join unions, but it generally does not cover independent contractors.

California seems to have some at-will variances for unions but it's still listed as employees. Should be interesting to see this play out.