California solved this by making speed limits not specified explicitly by the CVC unenforceable if they aren't backed up by a traffic survey. This will still result in places where the speed limit drops and local enforcement may try to profit from the drop. However, it stops local governments from reducing the speed limit arbitrarily for the purpose of creating a revenue stream.

Towns trying to juice out money from drivers happen at very least in Italy as well which is not Northern Europe at all. At least in NE this scales up for the wealthy as well. In Italy's case if you are rich you can just ignore speed limits (to a certain degree, driving licenses have points and you lose some of them when caught doing something illegal).

Right now, due to probation fees and interest, it's in the police's best interest to ticket poor people who pay more and cannot fight back. Having the police target wealthier people is strictly better, since they have the power and incentive to fight back against BS

But we should also take steps to fight policing for profit.