Not only you eastern Eurofags have that custom. I know in Spain it's the same.
Until I started chatting with people from the Americas, never knew that living with your folks is somewhere supposed to be a bad thing.
In fact over here the normality is for people to live with their parents until they get married. Yes, not the nerds, but the vast majority of people.
Most people in some places can't afford such huge luxuries and expenses just because they've become adults. Not to mention the fucking huge unemployment.