I wonder if there are any studies on how reliable this is, especially in a crowd. This can be very useful, but I see many ways how the assumption of "MAC addres

I wonder if there are any studies on how reliable this is, especially in a crowd. This can be very useful, but I see many ways how the assumption of "MAC addresses" = "people" can be broken: * As stated in the docs, not everyone has a phone, they estimate it being 70%, but I wonder how accurate this is in different regions for different crowd sizes and applications (cafe visitors vs a parade) * As stated in the comments, some individuals carry multiple WiFi capable devices and it can be much more than 1 per person * How large can a crowd get, before signals get jammed to a point this method stops being useful? * Many people prefer mobile data and sometimes even don't turn WiFi on So, I mean, it obviously can be used practically, but I struggle to estimate, how much should I believe what the device reads w/o actually seeing the crowd.