I disagree with Steam being wrong. It's kinda special situation where product also includes distribution on their store. So I consider justified of them having same pricing.

Now, I'm not saying that this should be apply to copies distributed via other channels. Just to those redeemable on Steam.

To my understanding, Steam does it to copies on all channels.

In this specific example. It is Bose that keep their pricing. And it is likely Bose and Amazon have deals that are not of the same percentage as other sellers. Just like Apple and Amazon's deal.