I drive across GA at least once a year, 80-90 mph are well within the safe norm for travel speed. The posted 70 mph maximum in GA is a bad joke that no one obeys and going slower than the average travel speed in the mid 80s on many rural stretches can be dangerous!! This kind of crap is happening all across the US today, many are like me and travel across many states every year. The best response I can come up with is buy a good radar/laser detector with gps tracking of speed traps along with access to the national speed trap registry. These speed traps are well known that are used to collect these fines and the speed trap registry can be helpful when you cross unfamiliar areas.
The most important thing you can do is know the laws in each state you drive across and make sure you stay under that state’s threshold for these silly fines!! And the best way to avoid this kind of surprise is to NEVER JUST PAY A TICKET!!! Always contact a local lawyer to see what your options are.
A trip across most of the US will show that posted limits today(65-75) are posted low by at least 10-15 to 20 mph, every state knows this. If everyone (85 %) are driving ~85 mph on the freeway then that should be what is posted. And these super speeder laws which exist in many states with big fines are a way states have figured out that they can take financial advantage of this.