When you hear someone say "young people" who do you think they are referring to? Personally, when I hear the phrase "young people" I think of 18 to 25 year olds.
I have heard the phrase "young people" quite a few times now. It's always used by ether teachers, or government and media types.
They often use it in conjunction with children, so they say, "children and young people are ...". Teachers at secondary schools will refer to their pupils as young people.
So, is young people the new PC code word for teenagers? Why the change? Why is an 11 year old at the end of year 6 a child, but 3 months later at the start of year 7 a young person? Something about that just doesn't feel right.
In my book anyone under 18 is a child and should really be referred to as such. If a differentiation must be made, use teenager, because everyone still understands that teenagers are children.