Well I interpret what you said is the reasons for light listening may be things like forced hearing while in a store or forced hearing in someone's car. Who cares? No one in that store or car is really paying attention or cares about what's coming through the speakers. As to " 'just to hear the traffic report' before going to a less frequented part of town." you are dreaming, who does THAT??? Let's see KFI gives a traffic report about Silver Spur Road in Palos Verde Peninsula or Portola Parkway in Foothill Ranch. Yeh, right.
Actually, we've seen tons of PPM data that shows things like a single quarter hour credit to KNX followed by
credit for the same quarter hour and the next one to a music station.
What happens is that a person checks traffic, listening for the required 5 minutes to get credit for the full quarter hour, and then switches station, with a minimum of 5 minutes to it... so both stations get full quarter hour credit for the same quarter hour.
(What I meant about "less frequented" part of town is folks... think of sales people, etc., who go to locations they are not as familiar with and frequent less... so they need a "heads up" as to any traffic issues).
Unless you understand the system of measurement, and thus the way stations can afford to broadcast, you are going to continue to suggest things that you don't think people do but for which we have ample and overwhelming empirical evidence of actually being done.