That makes sense, although it's not a subpoena in that case. It's just Amazon voluntarily cooperating. However, I'm not a fan of such voluntary cooperation. I think a company's default response should be, "We'll help you in every way possible once there is a warrant."
I mean, something like this should be viewed in the context of comparable IRL vendors. If I rent a 3rd-party storage unit from U-Haul or similar, a warrant is generally required.
(one exception I found was a case where police, on-site, witnessed a drug deal. They then used the defendant's key to open their unit without a warrant. It was judged lawful, that finding drugs and keycard on the defendant was sufficient probably cause. That makes sense, given that if police witness you in front of your house, or car, etc selling drugs, that would be sufficient as well to search.) [0]
