Actually, SAG pretty much covers the entire United States, so talent pools in LA, Dallas, and New York are all under the same union. The union/non-union thing is a major misconception.
I never said SAG was limited to just Los Angeles ... I used that as an example because there's a tonne of pre-lay recorded there, as well as a healthy amount of anime dubs. Yet you don't really see much crossover in casts because of what's done with SAG vs. what's not.
Funimation and Sentai's locally produced dubs are not unionized. They're based in Texas specifically because of lax labour laws. Reportedly, Funimation pays starting actors as low as $30/hour, which is below half of SAG's dubbing rate.