We have always had technology to detect this, it is just a matter if it was on. A few decades ago the NYS Thruway caused a bit of political controversy because

We have always had technology to detect this, it is just a matter if it was on. A few decades ago the NYS Thruway caused a bit of political controversy because they started issuing speeding tickets if you traveled between two tollbooths faster than would be possible going the speed limit.