Recursive law-breaking. Using the scanner while breaking the law is breaking the law, so by breaking the law while using the scanner, you're also breaking the law...while using the scanner.
Kinda like using a gun in the commission of a felony...is a felony.
Or being arrested and the only charge is resisting arrest.
I think of it more as computing something in "two passes". First, decide if the person committed a crime not in that "tack-on" category. Then, evaluate which "tack-ons" are applicable and possibly make those charges.
In Indiana it’s illegal to possess one while committing a crime, so even speeding with one installed, whether you’re using it or not, invites more legal difficulty.
https://www.zipscanners.com/resources/are-police-scanners-le...