Implementation requires specialized skills for the hardware, software, and logistics, as well as lots of time, money, and patience. A stalker isn't going to deploy many pi zeros with cameras in many places on his own, and I'm not concerned that they will be able to round up many assistants.
Amazon's product takes care of all that nitty-gritty, thanks to the work of their many bright employees.
If a stalker isn't going to deploy many pi zeros with cameras, then Amazon isn't useful to him either. It's still up to the customer to actually take the images.
For implementing facial recognition, yeah, it takes a little bit of coding skill. Same as integrating with Rekognition.
Amazon's product takes care of all that nitty-gritty, thanks to the work of their many bright employees.