It is work from which the company derives value in the form of reduced shrink. Furthermore travel to and from work is at the employees discretion and direction they are free to go not only just to and from work but wherever they please and their employer can't be expected to know, care, or pay for it.

This is more akin to being locked on the company premises after work has terminated unpaid but unable to leave. If they can't do a bag check in 5 minutes and leave amazon should hire more checkers to do that work or compensate the employees for the time lost.

Perhaps the proper thing to assert is imprisonment instead of wage theft.