I think companies should pay employees what they are worth, after taking a fair cut. Common opinion is that should pay what they can get away with, using any and all cultural forces, information asymmetries, etc available to them.
One of the ways companies pay women less is by taking advantage of the fact that women are less likely to think they are worth as much as they are. It's easy for companies to take advantage of this things, so they do. I still think it's wrong.
I won't think less of you for disagreeing, because as you say it's quite normal. I would say it's a common wrongdoing. Many/most employers aren't aware of the harm they are causing. And common (therefore often subconscious) wrongdoing is a lesser evil than conscious wrongdoing. But it's still wrongdoing.