It's far easier to test in Jamaica, it's a small very well connected island and incidentally highly preferable a place to live than 95% of America
America's testing is amateur compared with, for example, Britain who have chased their athlete's out of season down to the ends of the earth for decades and yet America still shows up as dirty.
All the Bolt bashing and bashing of successful athletes generally is envy and a sense of American entitlement to win the sprints, even though most of their medals have come from proven or self confessed dopers.