The argument goes this way: appointing a policeman’s position through popular car navigation app Waze, other drivers will drive more slower through that area and so Waze enforces the driving rules better than police themselves. But it doesn’t — and legitimizes dangerous behaviour.
Imagine being a not-so-nontypical libertarian, believing that when he can drive, speed limits don’t matter. What will you do, when you find a police patrol icon on you Waze map? You slow down for that particular turn to avoid ticketing, but then you speed up without worrying about any subsequential controls, because Waze tells you its safe. Or better: you speed up and take the shortcut on the parallel road, laughing about how you outsmarted those stupid guards, racing 120 kilometers an hour through the countryside village.
In the end, Waze legitimizes selfish (and destructive) behaviour of drivers, who forget that they are not in the ideal world full of perfect racers like them, makes overconfident drivers more dangerous to others and thus practically refutes the initial argument.
Speed limits exist for a reason and Waze makes it too easy to forget it.