At senior level, Scotland, under Scott Johnson, finished third which marked notable a improvement in recent years and Lineen wants to see more belief.
"There is a history there which ¬suggests that Scotland at under-20 level will struggle, but that is past," he told the Scotsman.
"Just as we are doing with the pro teams, in creating an environment where there can be no excuses, we are developing a structure at youth level that is more professional and that will prepare players better, in terms of their skills, strength and conditioning, their mental agility and their mindset. Guess what?
"We have good players, some very good players, and good coaches working very hard at all levels in the game in Scotland, but sometimes we don't believe that.
"Like New Zealanders, we tend to not want to stick our head above the parapet, in case we're laughed down. That has to change."