I've seen companies where you can have 2 devs working on the same project, one making say $30,000-40,000 and one making like $60,000-70,000. They do the same work, but have wildly different valuations because of their ability to negotiate.
If people negotiated higher rates and fewer hours, that is entirely possible to achieve and eventually could be the norm, but most people don't negotiate for anything. They think an extra $2,000/yr. is a big win, but then turn around and work an extra 10 hours a week at a job they hate.
The value in unions was that they would negotiate harder than individuals will. They perhaps outlive their usefulness and aren't great as an entity that should last forever because demanding more money every year doesn't always work if the company isn't having a good year, but the point still stands that lack of negotiating power is a problem.
C levels executives make outsized amounts of money because of 2 things - the higher you get in an organization, the better you probably are at negotiating (otherwise you wouldn't make it to the top), and many have agents that negotiate on their behalf (just like pro athletes).
I'm not an expert at negotiation, but I do know that the people who know how to negotiate well can get wins that the average person can't comprehend. A lot of people could negotiate their way into a 4 hour workday if they tried, they just don't know how.