I can drive 55, but the officer can say I drove 65

This makes no sense to me at all:

The Ohio Supreme Court ruled yesterday that a trained officer's visual judgment is enough to cite a driver for speeding.

In a 5-1 ruling, the court said police don't need radar or laser evidence to confirm what they judge with their own eyes.

What am I missing here? This seems to be a terrible precedent to set. 'Oh sure, you think you were going 55, but I could see you were going 65. Your speedometer must be broken. Oh, and by the way, my word is final, so you're screwed. Have a nice day.'

Let's hope they don't have a finding like this in Arizona, because if they do, then an officer could pull anyone over under the auspices of thinking that they saw they were speeding without having to provide any sort of justification.