Yeah, there is - California does not have a Right To Work law and is a closed-shop state. Surprise!
I think you’re confusing a new business with an existing business, or union work agreement? That doesn’t make unions mandatory. If a new business goes in, the union will have to organize a new effort.
Penske has operations in Cali, large ones, and none of them are union that I know of. Have you ever been underground at Longo?