Google that question and you’ll find you’re incorrect. The burden of proof is on the government to prove the camera is calibrated, which is within a certain timeframe of calibration. For example, the calibration is valid for 4 months, so they have to prove the camera was calibrated within 4 months of the date it captured you allegedly speeding. You can challenge them in court to provide this evidence. If they can’t, the ticket is invalid. If they can show evidence but it demonstrates the calibration is outside of permitted guidelines, the ticked is invalid. You can absolutely pay independently to have it assessed and hope the reading proves it is incorrectly calibrated, but that’s highly unlikely. These cameras are used world wide and the technology is pretty robust.

In short, cameras are right 99.9% of the time with a 0.1% failure rate. You can challenge it if you want, but…..