This is an economics article, but it's fairly short. It's from Wall Street 24/7 so it has a financial bias, but it has some interesting things to say about why wages are going down for most people and up for CEOs. Note that the worst cases are female CEOs. ( I have a guess on why that is.) It basically says that mergers and acquisitions are the culprit. I think that's part of the story.
Find it here: https://247wallst.com/economy/2018/05/23/why-are-ceos-paid-361-times-more-than-their-average-employees/