[piniondna]

I’m currently working on a similar proprietary system that is similar to the one described in this article, and I can tell you that there is much more involved here than “counting people in a room”. Claiming someone with a clicker in front of a door is a better solution misses dozens of other use cases where this isn’t at all possible or cost effective...

But you know, everyone on HN is an expert in everything.

[afar]

This. People are weird. They do strange stuff and it's really hard to count accurately.