Who is "we" and who is the "they"?
Unfortunately I don't think this is a "now" problem and if we look at history and how long it's been from certain events, these events were never "fixed" they were never resolved to a point that we can say they're happening again as if they weren't happening for a while. If we look at a time line we see how close these events are to "modern time". The last confederate soldier died in 1951, and the last union soldier died in 1956 which is in living memory, those people lived through a time where slavery was legal. Looking at the Nazi group there are definetly people who are alive from WWII, there are American soldiers who are still alive, there are Holocaust survivors who are still alive, so there are definatley Nazi solidiers who are still alive. What is different about the "now" is that the media makes it so easy to find people who align with one's political beliefs no matter how extreme they are. It is easy to find people nation or even worldwide who have similar beliefs and once you surround yourself with people with some extreme beliefs, they build off each other until it becomes something almost impossible to contain. We saw in the PBS documentary that he was flying all over the country to try and interview people about the clips for Charlottesville, and when he was attempting to interview the leader he was in another country organizing there. Now this is coming more mainstream news, I think that's why it can be considered to be happening "now", but unfortunately this is a problem that hasn't been resolved and probably won't for a while.
What we see in Charlottesville is a mob mentality, people with outrageous views are surrounded by people with more outrageous views, and they continue to build off each other. And with the political environment at the time, there weren't any repercussions for the situation. Due to the fact that this group has been building online, there were enough people from around the country to come and riot in Charlottesville. What is motivating them is a variety of factors, there is the mob mentality taking place, the idea that people with extreme views can connect to each other all over the country/world, and they are fueled by hate violence and the idea of change that doesn't absolutely benefit them.
Something that makes me beyond frustrated, is what they say they stand for so it doesn't come off as total blatant racism, they'll say some bullshit (pardon my french) that they stand for America and it's ideals, BUT they'll carry the confederate flag or bear the nazi eblem, two symbols that are so against america and it's "ideals". So many Americans died in order to get both of those to end, the Civil War was the bloodiest war on American soil so many american troops died to stop the confederate flag from being flown. So many American fought and died in WWII in order to put an end to Hitlers reign. Yet these people (and I use the word people with hesitance) show these symbols and claim to be for America or in support of America. Also what is ironic and so infuriating is that ALL of them are white, not one is native American and they will make claims against immigrants, or be against/ look down on those who immigrate to the U.S. As though their family didn't immigrate there, hate to break it to them but my assumption is that most of their ancestors came from Europe and they didn't get into America legally then, they were escaping famine, political dangers, and seeking new opportunities, and during the european migration Elise island was just open for business (not to say people didn't suffer, or get turned around or being an immigrant at this time wasn't hard because it definitely was, I'm saying that becoming a citizen has gotten so much harder and takes a lot longer that there's no possible way all those people are here "legally"). So people who are members of neo nazi groups, will say or advertise that they are for America and it's "values" yet, do the exact opposite (quite literally the opposite), which proves nothing motivates them more than pure racism and the fear of a society where cis white males are the leaders.
They'll bubble themselves off into a group and not stray from that group's ideas, because they are only surrounded by people who share their beliefs, they won't even consider another person who isn't exactly like them which is so dangerous as we can see throughout the documentary.