We call it ALPR - Automatic License Plate Recognition and it is both controversial and omnipresent. Average speed checks are not a thing here, ALPR is used primarily for toll collection ("pay by plate") and secondarily for law enforcement and asset reposession. (If you drive with a suspended license or don't pay a car loan, a mobile ALPR may bust you) Most plates are still legible to these systems despite the decorations - the remainder are verified by hand for applications such as toll processing.
People do stuff like obscuring the plate with a bike rack, a magnetic leaf, tinted license plate cover, etc, but it's a risky game to tempt the toll collector like that.
> People do stuff like obscuring the plate with a bike rack, a magnetic leaf, tinted license plate cover, etc
Just get a Tennessee plate -- they decided to use a background color with a text color that both show as the same under IR, so most ALPRs can't read them (at night at least). They refuse to change it, last I checked.
There are average speed cameras on the A9 here in Scotland - which I think have been a good thing given the reduction in insane driving I've seen on what was already a very dangerous road.
I personally am a huge fan of average speed cameras and think we should adopt them but that is a hugely unpopular opinion here in the states... it would be career suicide for a politician to campaign on that, quite possibly even for the deadliest roads with the most insane drivers. (For me, instantly thinking of the 'Robert Moses style' New York state parkways [1])
It's easier to just use the beacons from the tires, anyway. Doing it from cameras seems like going the hard way.
When I lived in Texas, toll roads were just starting to become fashionable. People worried that the toll tags would be used to give speeding tickets, so a law was written preventing police from using that data for that purpose.
People do stuff like obscuring the plate with a bike rack, a magnetic leaf, tinted license plate cover, etc, but it's a risky game to tempt the toll collector like that.