Glen Mills isn't a chemist, he's been a life long track coach.
And the testing is the same all over the world. You let them know your location and they come see you during a certain window and if you aren't there you get a violation (see Chris Coleman). Jamaica is severely underfunded in sports, there is no way they have the capital to do what the Russians or Americans were doing in the 80s. It's just genetics and better training, and more stringent drug testing protocols for all so the playing field is more level. We had some sprint queens in the 90s but they never got gold, the current generation is the off shoot of that. Big up to Merlene Ottey, Juliet Cuthbert.