Right. It's even conceivable that a programmer's union would actively oppose side projects and/or open source. Possible reasons: first, developers who participate in them will have stronger resumes, which creates an unfair expectation that you should be doing uncompensated work outside of your job. Second, the existence of free software devalues the work of paid developers. Companies shouldn't be using your open source project for free; they should be paying for union-built software.

I entirely disagree with those arguments, but I could see them being appealing to "501 developers" (https://501manifesto.dev/), and they're the majority.