You work in Indiana, which is covered by Central States, in which the union has negotiated a wage that's effectively $15/hour -- 50% more than UPSers earn in other places, including California.
Indiana minimum wage = $7.25, which is what most employers are offering for seasonal employment
UPS driver helping wage = $15, as a derivative of the collective bargaining agreement.
Say you worked 100 hours in December, you'd earn $725 at a non-union job and $1500 at this union job -- more than DOUBLE. And you're upset with the prospect of paying $37.50 back in dues? Seriously?
This exemplifies everything wrong with RTW.