It’s only because they’re not corporations, and corporations are people. When corporations love each other very much, they can bundle their money and make SuperPACs of DOOM!
Of course, when the people band together to fight corporate influence and exploitation, that’s wrong. When their organization chooses to donate to a political cause or candidate, that’s corrupt. Yeah, totally makes sense.
People organizing = unpatriotic, corrupt union
Businesses organizing = US Chamber of Commerce.