Italy has the speed averaging system (called Safety Tutor). The cameras are well indicted and are located in overhead signs. The challenge for drivers is that while the speed is usually 130, when it is raining it drops to 110. THe police then decide which to apply. From a driver's perspective you do not know what the police have decided. Clearly if it is sunny or raining, you can decide. But when it is raining for part of the segment (they can be 30 or more km long) you really do not know.
Mostly it seems that it is just a higher toll on the highway!