Because we, Americans as a whole suck when it comes to having a collective tolerance to battle COVID

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Olympics: The world is ready to head to Tokyo, but Tokyo isn’t ready for the world
Japan, like much of east Asia, has taken COVID-19 far more seriously than the U.S. has. Its collective tolerance thresholds for sickness and death have been far lower than those in America and Europe. That’s why, by Western standards, Japan has been so successful at preventing sickness and death. Since the start of the pandemic, fewer people have tested positive for COVID in Japan than have died from COVID in the U.S. Japan’s total case count, some 517,000, even when adjusted for population size, is less than what the U.S. tallied over six days in January.
That low tolerance is also one reason the Japanese public is worried about the Games. Foreign spectators have been barred, but tens of thousands of people will still be traveling to Tokyo. Their movement and community interactions will be limited, but not entirely restricted. They won’t be completely bubbled up. There will be some risk of spread. “If the Olympics were to spread infection, then what are the Olympics for?” wondered that same senior Japanese government official, Toshihiro Nikai, secretary general of the Liberal Democratic Party.