(b) Nothing prevents UPS from solving the problem at any time by simply and unilaterally raising the part-time wages.
There is something that prevents UPS from unilateraly raising part-time wages. It is called the reality of a competitive market place. UPS is losing market share continually. UPS is unable to compete on price and competes mostly on service. If we raise our costs by unilaterally increasing the part time pay we have to recoup that cost somewhere. Prior to a contract negotiation, we cannot recoup by reducing the cost of the full timers. If we try to recoup by trying to get more and better quality work from the newly better paid employees, the union will fight any and all more and better work standards we might try to implement.
To suggest there is nothing stopping UPS from just unilaterally paying the part timers more is just as silly as suggesting there is nothing from stopping you from paying more for your cell phone every month.
(c) The wage rates are minimums. UPS can't pay less, but they are free to pay more, just as they are free to make contributions to charity or give UPSers turkeys and other things of value.
(d) Running a Company involves evaluating the situation and spending money if circumstances warrant. But UPS Management has spent the last 28 years lamenting that their hands are tied, when it's really their thinking that's tied in knots.
I am not suggesting that UPS cannot unilaterally start paying the part timers more. I never meant to give that impression. As you say, running a business requires evaluating circumstances and using resources available and plan for utilizing resources in the furture. If your costs go up in one area (such as part time labor) you have to recoup those costs somewhere, either cutting them in another area or increasing prices, which makes you less competitive.
Are UPS managers hands tied? Certainly not completely, but there are restrictions. UPS cannot declare that the part timers will get the raise that was planned to go to the full timers this year, keeping the books balanced and easing the desparity.
During contract negotiations, it is not UPS job to fight for higher wages for part timers any more that it is your job to fight for a higher selling price when you are buying a home. It is the unions place to negotiate for higher wages and better conditions for all of their members. To fail to successfully fight for higher wages for a group you represent, and then try to say it is UPS fault, because they agreed to a minimum and they can pay more any time thay want is just a non sensical argument.
It would be like a cell phone company hiring a contractor to negotiate rates with a customer for service. When the negotiations are done, and the phone company realizes the rates the contractor negotiated are way too low, they complain to their contractor, and his reply is, well the rates are a minimum, the customer can pay more if they want, nothing is stopping them.
I suppose it is not entirely false, but it smacks of refusing to take any personal responsibility for what you are supposed to do and it is just a silly argument to make.