From Dragon Ball wiki:

[quote]Scouters also serve the purpose of gathering information, and for interstellar communication, as seen when Raditz sent Piccolo's description of the Dragon Balls to Nappa and Vegeta, as well as Frieza learning of the existence of the Namekian Dragon Balls from eavesdropping on Vegeta's conversation with Nappa (as well as Vegeta in turn learning how to get the Namekian Dragon Balls from the Namekian Villages via eavesdropping on Frieza explaining how he himself did so). Vegeta also used his scouter to keep track of the time after he said he and Nappa would give the Dragon Team three hours for Goku to arrive. Scouters can also tell the location of someone, as demonstrated when members of the Frieza Force use scouters to hunt down enemies.

Some members of Frieza's army, that are too weak to use ki blasts, wear an Arm Cannon that has a wire that connects to their scouter. It is unclear what role the scouter plays in using the Arm Cannon (some soldiers who lack scouters instead have the wire connected to a helmet on their head). One explanation is that the scouter is used for aiming, though this is not expressly stated.[/quote]

So yeah, Scouters are actually super useful for other things besides power level scanning. I'd be willing to bet they can perform other types of scans as well (like thermal or radiation) and are probably capable of some form of night vision functionality as well. That's on top of the actual canonical functions seen within the show that the above from the wiki describes.