Apparently, to take the processing off of the camera chip, the decision was to:
1. Not use a filesystem on the SD card;
2. Write RAW files only
This means software is needed to both transfer files, and to convert them into an image format.
Personally, I'd put that software on board, with extra dedicated hardware if necessary (it can be powered off of USB), and make the device appear as a massage storage device to a USB host.
However a security camera that works with all operating systems just needs to expose a drive via USB… as has been done for decades now.