There's a lot of reasons for this but one of the largest is the near invisible (to me) structural shift from direct hire to contractors for jobs at the lower end of the wage/salary spectrum. There is a fantastic long form article that articulates this better than I can at: https://highline.huffingtonpost.com/articles/en/poor-millenn... The portion relevant to this discussion: "Thirty years ago, she says, you could wa…
The question is why these services exist? I don't think it has to do with wages, I think it has to do with the difficulty of firing employees.
In that regard the sales pitch is similar to how Microsoft can sell a company email and word processing so that the company doesn't have to figure out how to write business software.