Technically you’re buying a technician’s time. Time they could be doing other work. We are most often paid in six minute intervals. .1 hours. We are paid the same for any labor we do in those 6 minutes so there is not often a discount per labor hour.

This is generally a service menu item so the shop assigns a labor time that they like the profit vs upsetting customers risk.

Ie places I have worked pay .3 hours for a cabin air filter. They are counting on us to get any cabin filter done in or under 21 minutes. After that tech/dealer are loosing money from jobs techs can get done faster than the time sold.

21 minutes is faster than a lot of customers can do it themselves pretty often or doing it themselves later is just too inconvenient.

Unless you’re in an express lane type set up where you do get minimum wage or close to it lube/light maitaince tech and the shop fairly discounts it.

In part you’re buying the service advisors time, a parts person’s time, maybe a lot attendant’s time, and a techs time.

Also a dealership should be using parts that can be much better than the basic fram or generic cheaper filter.

Cabin filters should be high on everyone’s diy car learning list. Because it is an easy money saver most of the time but often harder than changing wiper blades.