One summer when I was working in a Shell station, the business owner put a commission on every air filter that we sold at the "Full Service Island".
Back in the day it was easy to open the hood to check the oil, and then check the air filter by spinning the wing nut off of the air cleaner. That summer I bet I replaced air filters on about each car that I checked showing the dirty filter to the owner. There were plenty of them that looked like that one, and no I didn't try to replace filters that did not need it.
I did however did not like it when an older VW pulled in with the old oil bath air cleaner......no potential sales there. The only good thing about them was that a fill up took only about 5 - 7 minutes.....LOL.