People who want to abolish borders are often very naive, many have good intentions, but to believe that this society is ready for that does not make sense.
Look at what happens with the immigration of Venezuelans in South America, the crisis of socialism makes millions flee the country, there have been violent confrontations on the border with Brazil, and similar problems exist in Peru, Ecuador and Colombia. And there is not much racial and ethnic difference there.
Those who want to make a reductionism and bring the issue to the ethnic or racial are eurocentric, don't see how massive immigration is also a problem in countries in other regions, and worse yet, don't see that the mass departure of people from a single country it causes that country to have a brain and manpower drain, preventing them from recovering.
The difference between legal immigrants (beneficial) and illegal immigrants (problem) is big, and even anarchists should recognize that there is a problem there, because even if there were no borders you should not expect to reach a country breaking and stepping on its rules, moral values, and rituals, breaking laws when arriving in a country is exactly this.