Actually, it is voluntary.
First, there is little workplace listening where one person hears the radio of another in a different demographic. Usually, workplace listening is done by a group of like-minded people who all have a station they like, such as a group in an auto repair shop listening to a Classic Rock station.
Otherwise, "office" listening, if any, is some kind of paid service or a company audio program like that at Walmart or CVS stores.
The reason why AC, Classic Hits and Classic Rock show in 18-34 is that the listeners to traditional stations in the CHR / Urban and Churban genres have gone, in significant percentages, to streaming. So the remaining 18-34 listening is often to stations that have more limited appeal in those demos but which have always had one side of their core bell curve among younger demos.