It is not me "changing my argument" that you have spent several posts sniping at my arguments without apparently having the slightest idea what collective bargaining is.
Also, a salary agreement between a single individual employee and a huge corporation has by definition a huge power imbalance. Unions reduce that power imbalance. You can argue which is best (full negotiation freedom with massive power imbalance vs. collective bargaining with or without variable/performance pay and a much smaller but still non-trivial power imbalance), but there's no point in just arguing for one skew and ignoring the legitimate arguments for the other.
As I pointed out a very obvious situation in which power imbalances ensure even the best performers would benefit from collective wage bargaining from the very beginning, I'm pretty confident I am not the person in this subthread arguing for just one skew. But I am equally adamant that there are people Google considers [near] indispensable, and most of them are plenty employable enough for wage bargaining to be skewed in their favour, an imbalance not improved by people who want others to see pay rises first taking over negotiations.
Your "by definition" is incorrect. There's no law that requires a collective bargaining agreement to enforce pay maximums (or in fact anything about pay at all!). So please don't tell me that I don't know what I'm talking about.
Why would we advocate for this though? You keep making the claim that unions would advocate for more and more restrictive policies.
First it was guidelines, now it's strictly regimented salaries with no room for performance based pay at all.
You're generating objections because you keep changing your argument. Yes, paying everyone exactly the same is probably not a good idea. But no one is advocating for this, so who cares?