No offense, but the reasons most "scabs" don't want to join the union have nothing to do with that. What have the Teamsters negotiated for you lately? Because what most of us "scabs" and a number of your brothers see is a wide open concession stand.
Fix the leaky boat if you want people to come aboard. Most people don't see how union can help them.
And the attitude you take of referring to non-union drivers as scabs is something that non-union drivers don't appreciate. It makes you look like a pretentious snob. It'd be a vastly different, and more justified, case if a non-union driver worked in a union shop, but blanketing everyone that isn't a brother as a scab just makes people not want to be associated with you or your little club. Treat everyone like they're actually welcome and maybe they'll join.