Not uncommon here in Ontario , Canada , is having folks passing you when travelling 140 in a hundred kilometer zone on any of the 400 series highways .
But , generally , and police officers have told me this , they won't bother paying much attention to you unless you're 15km over , in most places .
Maybe not school zones , but most others .

I remember a time when down in Kentucky , I learned quickly that the slower speed zones was where you needed to follow the letter , or , rather , number on the sign .
Just about tipped over the camper van , entering a 30mph signed bend , at about 37mph , flinging dishes and luggage in an adrenaline soaked 1974 Ford Econoline 200 tank slapper .