I honestly can't tell if you're trolling or not. They would want to pass you because human drivers aren't rigidly law abiding machines. Is there a large portion of people that go exactly the speed limit, or even lower? Sure. Is there also a large portion of people that speed virtually every moment they're behind the wheel? Yes, absolutely. And I wouldn't be surprised if that were the larger population in most areas. No one who actually drives with any regularity would ever be surprised that people are speeding to pass them.