I got stopped, but wasn't ticketed, only a warning, for doing 67 in a 65 zone on I-44 in Oklahoma some 25 years or so ago. It was a sunny and clear Sunday morning and I swear that the only two cars on the highway that morning was me and the cop. He was even going in the other direction and had to drive down into the medium and up the other side to get into my lane. He said Oklahoma had a 'zero tolerance' policy (claimed that was clearly stated on signs at the state border, but I never saw it) but he let me off with only a warning but said that my name was now in their system and that I wouldn't get a warning next time. I asked him if he had ever actually issued a ticket to someone going only 1 MPH over and he said YES he had, but that it all depended on the attitude of the driver.
I also saw once in Kansas where the state cops were pulling over people who were NOT speeding at all but who were simply driving high-performance automobiles like Mustang GTs and Corvettes, and giving them warnings that they watched cars like that extra carefully, just in case.