I'm tending to my scented Geraniums when I think about how they're not Geraniums at all--they're Pelargoniums. Due to centuries of mistakes (dating to the 1700s!) we still call them Geraniums. This is an example of a plant being called a name of a separate genus which still exists (there are "real" Geraniums).
But Coleus is another plant that I grow every year, and that genus (Coleus) does not exist anymore, as far as I can tell (correct?). Every plant I see called "Coleus" is either Plectranthus or Solenostemon. But we all still call them Coleus.
I'm guessing there are a ton of examples, but by their nature common names are so common that we probably don't even realize it (I don't, at least). And when the common names are a current or former genus name to a similar or related plant, is it any wonder people get confused?