Seems if cruise control runs off GPS, it is more ticket reistenat than the speedometer running off tire rotation. Agree they really should match, but shouldn't setting cruise to the speed limit be at least a defense in court? I know going to court is also a pain, but citizens should fight against tickets based on such minor infractions.
While there are some hard speed limits in the US, such as school zones in Tennessee (not only is it zero tolerance, it is reckless driving which is worse than simple speeding). For almost everywhere else, "reasonable and prudent" is our standard. Nice sunny dry clear day with no traffic on a straight stretch of road posted at 45 (curves maybe earlier or later), 50 will not result in a ticket in that stretch. Add traffic, rain, poor visibility, 35 may result in a ticket. Actually more sane than an absolute number even if somewhat subjective.
We also have white signs (posted limit) and yellow signs (a lower recommended speed for perhaps a curve). Barring safety factors, the yellow signs do not carry the same weight (no speeding ticket) if negotiated safely but it is an area where enforcement of the white sign carries more weight than that nice clear sunny straight empty stretch of road.
My last interaction with law enforcement over speed resulted in a warning, not a ticket. The office pulled me over due to a headlight out. In the daytime, on a clear day. We also have primary and secondary infractions. Without the speed (primary infraction), he could not stop me for the light (secondary). With the speed, he could stop and cite me for both. I thanked him for letting me know about the light and apooligized for my inattention to the speedometer, was just going with the flow of traffic.
Are Aussie cops really that strict? Ours are generally human if treated with courtesy and respect.