A ton of stuff is done on mobile terminals. Computer aided dispatch including status and location of a unit, report writing, identity checks, etc. Scanners were useful because a cop would ask the dispatcher for a license check on Joe Blow, age 34, of Smithville - or registration check on a certain license plate number. These days by the time an officer flips on his lights to pull someone over, they probably already know the registration/insurance status, license status of the registered owner, their photo, etc.

Then there's email and other messaging for lower priority things, and phone calls for stuff that is sensitive.

This is a problem when the computer is wrong. I've been pulled over for having "unregistered" plates that were perfectly valid.