You're right in principle. This is definitely the case if I ask the company to deliver a package, for a price that they name (or negotiate), and I then hand ove

You're right in principle. This is definitely the case if I ask the company to deliver a package, for a price that they name (or negotiate), and I then hand over the package and money and let them do their thing. The issue here is that Amazon is very strictly controlling the drivers, without (directly) employing them. By gig-economy voodoo they try to have it both ways.