Obviously one reason that you can get better talent from nations other than the US is that in the US there are a great number of outstanding runners not running. They are playing basketball, or swimming, or soccer, or baseball, or lacrosse, or ice hockey, or volleyball, or motocross, or ad nauseum. In Europe, Africa and Central America there are a handful of sports most school age kids can pursue, 1- soccer, 2- track / x-c, 3, 4 & 5 (add sport of regional interest here- basketball for some, rugby etc). Also track and x-c is a cool sport in those areas, and is not the "other" sport that HS do.
In short, imagine how much better US running would be if every high school kid who was going to do a sport HAD to do track, thousands of highly talented runners would emerge, compete, winnow their numbers, and the product would be better elite runners. As it is, you do have some elite runners who wind up running, but the competitive distillation is not nearly as difficult or sharpening as fine as it would be if everyone, or even twice as many, got in the pool in the beginning.
That said, God invented wiskey to keep the Irish from ruling the world, apparently those coaches must abstain during training thus, they are kicking ass.