I don't know how other states handle speeding, but the PA state police give you a little leeway over the limit. They'll never say what the amount is, but it's probably in the 5-6 mph range.
There is a small town near me that was plagued with vandalism, home break-ins and such. They mounted cameras throughout the town and the police have caught many of these low-life's because of the cameras and it's lowered the crime rate substantially.
I agree, the 1 mph over the limit is extreme, but there is another side of the coin which is a benefit to property owners.