The issue is the exact same thing applies to your plumber. So either you owe him decades of back pay and healthcare or it is OK to hire people for a job and not keep them permanently...
My plumber can fix my pipes however he wants. He is a sole trader, I will pay him for his service.
If I sign a contract with him to go around other houses and make him fix the pipes the way I see fit, for example, using only black tape and stamp my logo on it, I receive the payments from the customers and pay him, he is my employee. People are not hiring him, they hire me and I employ him to do the job.
It's not even a marketplace, it's just me who finds the customers and the plumbers.
So, I actually think the directions you give the plumber are MORE specific. I won't accept sewage in my drinking water. I don't care if my Uber driver takes third street or 4th avenue.
But that's not really the point here.
The point here is that there used to be a pretty well defined line between the self employed and employees. That's not the case anymore.
So we either spend decades making ever more complex unenforceable rules, and pretending taxi drivers deserve more/less from their jobs than (say) plumbers. Or we man up and stop pretending this makes sense and use a different system.
Not at all, giving that kind instructions to the plumber is like telling the Uber driver not to hit and run women and children. You don't give instructions on the core job competences, if you do, you are a teacher not a client or employer.
