Then why are people still asked to wear masks in stores even if they are vaccinated? I've heard from the media non-stop that even if you have the vaccination you need to wear a mask - it doesn't make sense.

a) it's not entirely whether vaccinated people can still be carriers. I think it's now /mostly/ clear that they don't.

b) people are fscking awful. If you let vaccinated people not wear masks, you're going to have a bunch of philosophical zombies lying about their vaccination status to avoid wearing masks in public spaces. So, everybody wears masks until this thing is over and then some.