I am not sure that it means that kids are hard to teach. There is a dynamic of attention span. The attention span for listening to a lecture is certainly decreasing. This is due to age of media. It is not to be seen as a put down, it is more about the reality of our age.
Humans should be able to concentrate, focus on a subject or task for more than 10 minutes.
It is only reality if we permit the general loss of skills like attention to detail.
What's the point of learning every last detail of a technology if the technology will be obsolete after 10,5,3 years anyhow? Transferrable skills, meta-skills, and flexibility, that''s what you need to survive in a double exponential growth, high tech economy.