If I have a face and a city how much effort and time it takes to visit all places with cameras, search all the tapes and find that face? With a website like fa

If I have a face and a city how much effort and time it takes to visit all places with cameras, search all the tapes and find that face? With a website like facebook that can track a browser on most webpages , having to find a person internet history would be just a SQL query away and the results would be back in a few milliseconds, so IMO FB and Google tracking are very different then what you described. Also because of convenience people ignored this until the US election issue, that pushed a real problem in the spotlight and regular people now get amazed but what Fb can do.