UPS will not make a profit during Xmas season if it was paying every new hire $15/hr. It is what it is, and if you can get your foot in the door and gut it out, the pay and benefits are worth it.
Some areas have long waits for full time employment but I see many Part-timers in my building who are happy making $20+/hr for 4 hours a day and getting the best union benefits in the business. They have no desire to go full time.