There are more truck drivers in the US than just about any other occupation.
For a long time, unionized truck drivers benefitted from work rules, healthcare, vacations, etc. It wasn't an easy job to get, but it was a career.
Companies started to realize that if they offloaded the work to freelance truckers, people with their own rigs, they could take advantage of a free market. As a result, more and more of the work ended up with independent operators, who got to be their own boss, paying for their own equipment, finding their own work. (HT)
The problem, exacerbated by the speed and power of the internet, is that there's always someone cheaper and hungrier than you are. That if you do undifferentiated work, the market will squeeze you to do it cheaper.
We get (slightly) cheaper trucking. The millions of drivers get exhausted while living right on the edge. They work too many hours, carry too much weight, burn themselves out.
And the same thing is true for anyone who signs up to be a cog in a digital marketplace. Uber drivers, freelance bottom-fishers, hard-working people cranking things out by the pound…
Any market that seems to offer an easy in to the undifferentiated will eventually squeeze them.