I'm so used to hearing them in music & TV shows or films, media is all I associate them with & don't give it a second thought.
However for some reason, I still feel a little surprised whenever I come across someone IRL with an American accent of any kind - it makes me want to slap them just to make sure they're real.
I don't think I can explain it with "lack of exposure" because the accent is everywhere - so I'm not sure why I react the way I do. Maybe hearing it juxtaposed with the Aussie accent just throws me off?