The boy without a ticket

I found a curious article here on CNN.
It says 'Boy hops plane to Vegas, apparently alone and without ticket'.

A boy who is 9-year-old could get on the flight by himself from Minneapolis to Las Vegas without a boarding pass in spite of a lot of security checks and the crews. Fortunately, the crew made sure the boy's safety in the plane, but they still do not know how the boy could do it.

I think it is a wonder that the boy could enter without a boarding pass and he was alone. I have gone to some countries but it is impossible because the security at all airports was very severe, especially in America. Did not his parents or some people take care of him at there? If he was accompanied by them, this case never happened. It is possible that little children go anywhere with　their curiosity because they do not know where here is. Also, it is crowded with travelers at the airport, so people who have their little children should look at them carefully at all the time.  I also wondered if all crews did loose security because the boy was a child or not. Even though he is a child, I think passengers should be searched strictly whether they have their own tickets or not. If not, one or some of the passengers may have gone to other place or country as well as him. It is very dangerous and it will take much time and cost to fix it. 

What do you think which is bad, the boy or the crews and how the boy could enter the security?