Isn't it self evident that anything that grows larger and more diverse becomes more complex and difficult to manage?

More to the point, we have a large number of small airports that may service a couple of flights each day. Security people at these airports will by definition be less trained and a more diverse group, yet the passengers from these airports will be delivered and will blend into the secured areas of major airports. This is just one example of a problem that the Europeans don't face.

If you have all your eggs in one basket, it's obviously easier to keep an eye on them.