I tried to build something very much like "Tappy" as an internal testing tool, and with the limited time and effort I put in, #4 was definitely what prompted me

I tried to build something very much like "Tappy" as an internal testing tool, and with the limited time and effort I put in, #4 was definitely what prompted me to give up and go for a "screen capture over ADB" instead of a camera. There was glare, all kinds of distortion, noise etc, that while of course possible to overcome, was way out of my league to deal with. I guess one could have thrown machine learning in the mix too... :-P