An important difference between systemic and individual injustice -- or, if you like, evil --is that individuals in historically favored groups continue to benefit from the entire inherited structures of an unjust system, even if they didn't individually cause the injustice in their own lifetime.
Think of large German companies that continue to benefit from WW2, when their present success was founded on the concentration camp labor system; or museums that benefit from artwork that originally was stolen from Jewish families; or large international companies that benefit today from the manufacture and (often shady) trade of arms and weapons, or opioid drugs, or tobacco or alcohol. If the injustice was perpetrated over years or decades and the perpetrators were never held to account, you can't seriously address the problem unless you acknowledge that systemic injustice often requires reparations even generations later.
Or someone mentioned Zimbabwe far above -- the recent generations of white farmers may not have personally caused the system of grossly unfair land distribution, but they would have continued to benefit from it unjustly if redistribution had not been imposed. However brutally and in that case indeed unfairly, and shortsightedly, since the way it was done killed the agricultural economy. But that doesn't mean reparations are inherently bad or impossible, just that they have to be done with more genuine concern for all sides, and that the details do matter. Other countries like Colombia are slowly addressing the problem of land redistribution, with some decades and administrations seeing steps forward and others seeing steps back. It's never easy or quick, but that doesn't mean we don't have to make an effort.
On a smaller level, perhaps middle-aged white male academics didn't personally keep women or colleagues of color out of their departments, but nevertheless, they owe their jobs to a system that unwittingly favored them all along, made it relatively easy for them, from mentors to inherent assumptions of who would teach and publish. Similarly, modern Catholic priests didn't personally make the original decision to exclude women from leadership and decision-making, in a break from the early church. But they still benefit from a system that uses women's labor and women's bodies, but denies them an equal voice, an equal soul, personhood, and representation of the divine.
In all these types of cases, it doesn't mean that modern individuals share the guilt for the original evil. But it does mean that they are still complicit in a system that still benefits them unequally. So they do share the responsibility for changing the system, because they still hold unequal power within it. And if they fail to act to change the system, or at the very least to acknowledge the continuing injustice, then yes, they become guilty: guilty of inaction, of complacence, of walking by on the other side when victims still lie bleeding by the road, waiting for some other good Samaritan to appear.
Back to the particular subject of racism: I wish dude were still here to help explain, but perhaps other Americans can still contribute personal observations and experiences. Once again, I get the impression that many Europeans see the subject only through the lens of their own culture, so that they simply aren't fully aware of just how poisoned the entire US system has been for centuries. The red-lined neighborhoods where banks would not write mortgages for black people to own a house, so that generations of urban black poor families were segregated in slums. The way that sharecropping and convict agricultural labor replaced slavery in the south, so that generations of black farm families could never own their own land. The school-to-prison pipeline for young black men, starting with black preschoolers (!) being punished or suspended at higher rates than their white classmates. The fear of young black people today, in 2020, that if they are stopped by the police, however unjustly, they may risk death, not just inconvenience.
In the face of all that weight of continuing evil, 'I didn't start it' or 'It's not my fault' is just not an adequate response. Indeed, I have to say that it can come across as a surprisingly cold, even callous one.
In a post in a parallel thread, which I mentioned here far above at #111, I linked to a documentary film that I think might help Europeans understand the scope of the problem of racism in the US.
Siehe auch: Joe Biden's first language - #132
There are also other ways to educate oneself about the problem, from Wikipedia to other films and books, including others by Henry Louis Gates. American magazines and newspapers are doing a pretty good job of reporting the deeper issues. The information about the scale of injustice that still exists today is out there, if you look for it.
So. Like Norbert, I don't think some of the current manifestations of the problem, whether street protests in Portland or academics writing about white privilege, are doing much to solve the problem in practical terms either.
But I agree with Gibson that we should at least be willing to hear the cries of pain that they represent. And I do think that the stance of some previous European contributors in this thread, of brushing those manifestations off as if they were the cause of the problem, while refusing to even talk about the real generational and systemic causes, is not helpful.