When I was looking for my last job a company wanted me to sign something similar to that. I declined their offer and got a job elsewhere instead.

I feel like that's .. the reasonable take here? If you don't agree to their conditions, then .. just don't work there?

It’s basically true that everything about employment is a negotiation and if you don’t like the deal at one place you can try to negotiate it differently, or work elsewhere. Of course, unionization is a legitimate move in that negotiation.