Why do people consistently do this?

Are there some roads where the road markings are ignored because it makes more sense to get into the left lane for going left and right for going on straight?

Twice in a row in a place in the city centre I've come up to a place where my lane can go on straight or turn left and the lane in the left can ONLY turn left. I want to get in the lane on the right after turning, so I go in the right lane. The guy in the left lane HAS to get in the left lane after turning, right?

So why did I see two guys going into the right lane (after turning left) today and cutting me off AGAIN, without even indicating??? They probably thought I was the one who was at fault, and this happened twice in a row!!! Surely people realise that they have to look into other people's lanes to see where they can go after the lights???