The Injustice of Young People’s Pay

According to this blog entry (https://minimumwage.blog.gov.uk/2016/09/30/new-minimum-wage-...), the lower minimum wage is for youths is to prevent youth unemployment. This was based on some data the government has (not specified in the blog) that indicates that that younger workers were being passed over in favor of older workers. That implies that youth workers are less valuable (or perceived as less valuable) and thus not worth paying a greater wage.

As an American, I find this pretty strange as most minimum wage jobs are low skill. Since the skill threshold is low, there's not much to be gained by experience, so an older worker isn't much more valuable. I'd expect this lower minimum wage to tilt the market in favor of hiring youths since you get roughly the same work for less. I'm curious to see what the governement's data actually is that justifies the lower youth minimum wage.