The U.S is not inherently any more racist compared to other countries.
Rather, the United States has a history of trying to deal with uncomfortable things by pretending it doesn't exist. Pretending Racism doesn't exists exacerbates it. Combine this with the fact that the U.S is one of the most diverse nations on the planet, and the result is that there are more instances where diverse people interact and this suppressed racism can flare up.
In addition, Racism is not necessarily as tribalistic as most would argue it is. Rather it is used to justify institutionalized practices by appealing to the ego. For instance, consider Slavery, which on the surface seems motivated by Racism. As slavery is not unique to a specific "race", nearly every race has been enslaved at some time in history, a motivation of Racism isn't necessarily a justification.
Rather Racism served as, and can continue to serve as, a tool to justify immoral actions in pursuit of more concrete motivations. It is much easier to sugarcoat the pillaging and looting of valuable natural resources as "liberating the heart of darkness" and "bringing light and happiness to the savages".
In this day and age, with the Internet, ignorance is a choice! And they're still choosing Ignorance! - Dr. Filthy Frank
