I was pretty upset about the four year progression happening right before I became a driver. Almost passed on the offer just because of it. Working out the numbers it's anywhere from a 30k to 100k hit to a new driver's bank account over 4 years depending on previous progression schedule you compare it to. The union has allowed the company to take almost the cost of a house away from me (in my part of the country). I started looking into how to go about getting a better union to represent us, since teamsters doesn't seem to care too much. I ultimately decided I should just do what I can to make the union better. Either strategy is probably a waste of time, but it's better than whining about it. Run for a trustee position in your local if you want to have any say over any part of contract negotiations. Stewards are only involved in contract enforcement, unless they are also trustees.
I will say that I couldn't attend our local's meetings as a part timer because I was on local sort, and my exposure to the union was limited, so I didn't have much of a clue about what was going on. New member outreach is likely an area where locals could improve.