I was under that impression until recently, but I heard some lawyers in one place half-jokingly talk about a case in which a car was captured on camera as speeding but no one could be found liable in court for the speeding ticket because the person driving was wearing a mask. I kid you not. This was in Sweden. And I do recall such a case in Arizona too.

Radar detector use by drivers in Sweden is ordinarily considered illegal in some places where use of GPS devices loaded with speed camera locations are not illegal.