Help me out, I still don't get it. Isn't "freeloading" a systemic feature of the labor market itself—i.e., it would be present regardless of whether right-to-work laws existed or not?

If there's a market where employers have offered to pay X to a certain group of workers, presumably the employers are willing to pay X and below for labor. Unsigned workers are looking to maximize their pay. Doesn't microeconomic theory dictate that the unsigned workers and the employers will settle on X as wage? In other words, if you are an unsigned worker and you see others getting paid X, rationally you won't sell your labor for less than X. (And if the unsigned worker is willing to undercut and work for less than X, so be it—it doesn't sound like right-to-work forbids undercutting this way.)

I guess my question is: wouldn't market forces (ECON 101 dynamics) prevail in allowing non-union members to benefit from union bargaining, even without right-to-work law? I'm sorry if this question betrays a sore lack of understanding; I'm just trying to get a better handle on how the labor market works.