There need not be any wonder or curiosity…
And, High Hopes, you have asked this same question, or more to the point, made the same insinuation about US distance runners not going to Europe and racing in other posts.
US distance runners are racing either USATF 10k championships and world championship selection race in nine days Friday night before Pre where other US distance runners are racing 5k, Bowerman mile, 1500m etc on Saturday. Many of these same US distance runners are currently training at altitude and would not jeopardize their preparation for worlds by taking chunks of time away from their schedule and impact their trading phase based on this years events calendar.
After worlds, those US distance runners that are invited to Diamond league races will most likely go to run fast against top competition and make some money. Others that don’t make worlds or aren’t at the performance level to be invited to Diamond league will go over and race in other races to… run fast against strong completion and make some money.
Not having much knowledge about the sprints; I’ll guess that sprinters are not faced with the same training preparation needs as distance runners and have the benefit to be able to race more, recover more easily, not have to be at altitude etc.