Some crimes the police aren't interested in.
Call them up about suspicious activity in your area or a parking lot accident.
I think the driving reason for private license plates here is customers for prostitutes.
With the new laws, it has become very difficult to identify stolen cars and isolate innocent from guilty for neighborhood groups.
So a great deal of police time gets wasted AND most of it never happens.
It is a terrific boon to criminals.
I once caught someone from a neighboring town spying on me (and very poorly too) because I was a witness in a police violence and corruption case there.
The police here refused to press charges because it involved corruption.
They backed off only because I had been able to identify one of the criminals spying on me.
You will find a similar pattern in many stalking cases too.
A common use is to track criminals casing a neighborhood.
For example, if a car prowling constantly traces to a real estate agent,
it is pretty safe to assume we can focus on other problems.
Until I have something to report, the police MAY write it down and then they will do nothing, until there are more crimes.
If you think the police do these things, you are deluded or live somewhere with a better police force than most places have.
Just as real estate information is public for valid reasons, there is no reason to hide your identity if you are using public roads.
No one is forced to use a car.
If it bothers you, there are many ways to scrub your information.