That's because defeating the webcam proctoring is trivial. The simplest setup is a teensy, allowing two mice to be shown to the system as one input device. A HDMI EDID emulator placed after the GPU and before the splitter for two monitors.

The second person literally doesn't have to be in the same room, and you could even get fancy with a PiKVM for your assistant to be remote.

The proctor cannot distinguish the two mice or monitors, because the computer cannot either. This is a completely unpatchable hole with no good method of detection.