Selecting Pop in Focus (and getting Rock)

I made a focus for pop in the 70’s
It gives me all things Pop (good), but definitely also things not Pop (not good).
I get Rock and Hardrock as well, and neither album nor artist have a tag ‘Pop’ / ‘Pop/Rock’ or any sub-genre of Pop. Example: Bob Seger & the Silver Bullet Band.
How does it then end up in my selection?