My parents pay no attention to pop music or pop culture, so if they don't know a certain singer, chances are the singer isn't really a household name.
They know Taylor, because they listen to country music.
They know Britney, because everyone knows Britney.
They know Gaga, because everyone knows (and has an opinion about) Gaga.
They probably know Beyonce (and JLo) because of their movies, etc... But not their music or performances.
They probably know Kelly Clarkson because of her country songs, but don't recognize her pop songs.
They know who Katy Perry is (but don't her music), because they know I can't ****ing stand her.
They don't know Rihanna... Mom only knows her if I mention the abuse thing (and it's been a while, so she may've forgotten).
They don't know Kesha.
They don't know Nicki.
They don't know Pink.
They don't know Xtina.