It’s the equal pay for equal work thing, stupid. Union strong and proud. (Bumper sticker on 1972 VW Rabbit, Vancouver, Canada).
Sure, that might be the mantra for the "new faculty majority" [increasingly organizing into faculty unions. Actually New Faculty Majority's is "Faculty working conditions are student learning conditions" but close enough], but in a large sense, the fight to normalize the work, pay and benefits of part-time/ contingent/ temporary/migratory/ irregular/ at-will/ auxiliary faculty, AKA “freeway fliers,” is one centered on dismantling the two-tiered system of inequitable pay and punitive treatment between tenure track faculty and non-tenure track faculty.