"Ryan Calo, a law professor at the University of Washington who specializes in legal issues related to technology, said Amazon’s new service relies on the same kind of trust homeowners commonly extend to services to which they hand over their keys. But he said those agreements often involve in-person interactions, which won’t happen when homeowners allow Amazon to unlock its doors.
“It raises questions about how do you specify and police expectations when the relationship is one mediated almost entirely by technology?” Mr. Calo said."