Why is it that churches cannot seem to retain the youth that grows up in them?

I had always thought that the reason that the church I belonged to was unable to keep their young people when they left home was because there was no university in the area, so people had to leave to continue their education. Even if they did not want to continue education, being inside the M25 London orbital road meant prohibitively high house prices resulting in young people moving up north.

However, there are two interesting articles that I have read recently that suggest this is not just a problem for the young people of the church I used to attend;

I am inclined to agree with what both write, as it agrees with my own experience. However, there seems to be a problem with how to deal with it. Brian McLaren suggests more open dialogue and more effort at understanding different viewpoints, but maybe this is an issue beyond the church and if the youth grow up to attend other churches that we should be content with that.

Maybe I first desire is for the youth to grow up into spirit-filled Christians, rather than achieving some statistical target for church youth retention.