I just finished reading a book about the history of the TRINITY project.
The government did try (and fail, obviously) to create an exclusion zone around the area, and they did have people all over hell with radiological equipment to measure fallout (some of them checked into motels and guest houses with their equipment in suitcases and posed as holidaymakers), but they clearly didn't fully understand affect, never mind that they didn't really know how big a 'boom' they would end up with in the first place.
They also didn't have a clear understanding of how far any 'downwind' fallout would travel. Add to that, the weather was iffy right up until they made the decision to go ahead with the tests, and the tests exceeded every expectation in terms of the potency of the weapon. I do think they would have preferred a more 'still' air environment but they believed--weather forecasting being the half art/half science that it was in the days before satellites--that they were within acceptable parameters. Clearly, they were dead wrong.
The government should compensate those victims. Time IS running out. Will the GOP Congress ever act? I doubt it strongly.