Here's the state code (Utah) on license plate readers:

Law Enforcement use of the ALPR systems is limited by 41-6a-2003 to:

(a) Apprehend an individual with an outstanding warrant;
(b) Locate a missing or endangered person;
(c) To enforce motor carrier laws, or
(d) To locate a stolen vehicle, or
(e) As part of an active criminal investigation.
(f) Troopers will not run ALPR data prior to, or during a traffic stop unless reasonable suspicion can be articulated for an active criminal investigation.
(g) Any time ALPR data is used, written documentation and a case number must be completed

It's very possible the police have scanned my license plate, and imo that's totally fine, provided my car is in public and one of the above apply.

From those:

1. I have no warrants, so this doesn't apply
2. Could happen to anyone, but chances are very low
3. I'm obviously not a commercial vehicle
4. Possible, but unlikely. I drive old, crappy cars, so my car is unlikely to be similar to a stolen car.
5. Again, possible, but I don't commit crimes worth tracking via license plate. Any crimes I do commit would likely fall under traffic violations.
6. I try very hard to not give police reasonable, articulable suspicion. If stopped, I give short answers and have yet to have a problem.
7. Police are lazy, so they're unlikely to use ALPR data unless they have a good reason. I intend to never give them that good reason.

I go after the low-hanging fruit so as to not arouse suspicion and protect me if there is suspicion. Going any further (e.g. trying to fool ALPR systems) goes against that. If I'm on public roads, I assume my car can be tracked, so I drive carefully and keep my car properly maintained. I also store any potential contraband out of view so as to not raise suspicion if I am stopped.

It would be nice to go even further, but I'm not going to break the law to try to hide, I'm going to blend in instead.