The real story is how much they charge company A to defend their search terms vs how much they charge company B to usurp company A's search term, ie they are using all their data to extract maximum rent and not running a "fair" auction.
I’ve run plenty of brand campaigns and the clicks tend to be an order of magnitude cheaper than running keywords on competitors keywords.
My experience typically lies with local companies though.
I see ~30%.
And again, this is only for local service businesses.
Is this your direct experience? In my campaigns it's typical for me to see 5% CTR for the keywords I target and then a ~30% CTR for branded terms (depending on the brand name)
Branded clicks are more than 6x cheaper than non branded so the CPM is still lower.
Again, that at least has been my experience. And regarding the "would have been free" argument, I've gone back and forth and have seen better results with branded campaigns than not having them on. But I've seen accounts where that was not true.