Yeah sufficient resolution is definitely an issue.
I'm not suggesting you can use models in all situations or an all current setups, just that it's possible (and surprisingly easy) to use models to automate a lot of analysis on video.
A lot of current commodity $100 cameras are good enough resolution for many use cases but of course you do need sufficiently high res video and good enough lighting conditions.
You also don't necessarily need to do facial recognition to track people. I'm nervous of the privacy implications of all this surveillance tech but it's possible to do useful tracking (e.g. I've worked on a project counting people to prevent over-filling busses which is a big issue in Africa) without needing to use facial recognition. In the counting case, you don't need to recognize people to count them and can do edge computing on quite low resolution video so that the raw footage never leaves the device (only computed count statistics).
