Property rights' moral basis flows from the moral principle that the de facto responsible party should be held legally responsible.
Property rights are deduced by the natural right to self-ownership.
"Though the earth and all inferior creatures be common to all men, yet every man has a "property" in his own "person." This nobody has any right to but himself."
The voluntariness of the employment contract is irrelevant because de facto responsibility cannot be transferred even with consent.
As I said before, you're denying the natural right of the employee to free will.
Every individual employs scarce resources to attain a desirable end. If you are against social cooperation, you're making human action more difficult.
"For a contract to exist as property, each contracting party has a property interest in specific performance on the part of the opposing contracting party. But a property interest in specific performance is not a property interest in the person. The employer contracts with an employee for specific performance. The employee also contracts with the employer in similar style. Each has a property interest in the performance of the other, but neither owns the person of the other."
Amazon is just another big company that benefits from corporatocracy.