It was the same in East Germany, and the East still hasn’t completely caught up 20 years after reunification.
Trying to integrate NK into SK would need a 10-20 year transition, if it all happens at once, Korea would be impoverished again for a couple of generations. It is a much bigger difference than east and west Germany.
and remember East and West Germany never fought a war against each other.
But the Eat German’s knew that what they lived in was not the way. These people don’t know any other and most likely wouldn’t believe you if told them so.