I've been following the history between the IBT and Yellow for the last 15 years or so and I've drawn a conclusion. I don't think the union BA's care a whole lot about the members best interests. I think the loyalty of the BA's lies with their bosses to keep the dues money rolling in and union members are little more than the means to that end. I think those who claim to protect you and your interests are playing you for chumps. Think about the difference between how the company gets paid vs how the union gets paid.
A trucking company generates revenue from customers by moving freight from point A to point B regardless of whether or not its labor force is organized. If the customer becomes unhappy with the service, they go somewhere else. The company has to deliver a modicum of quality to the customer in order to survive. Teamster Inc, on the other hand, isn't subjected to the same market forces the company is. They get their money from dues that will roll in regardless of the quality of service provided to the membership because that's the agreement that was made long ago when enough past employees voted the union in. As long as members are employed, Teamster Inc. will continue to thrive and they aren't going to let your interests come between their interest in the company's long term survival. You're not getting your money's worth from your collective bargaining agent because they don't have to care about you in order to get paid.
Start a company wide push for union de-certification and see what happens because nothing gets the attention of a company than the threat of losing customers.