I'd prefer to take the term "racist" out of the equation because it is inflammatory and makes it difficult to talk about what is actually taking place.
Western people, particularly men, are taught that they make their way through their individualism and rationality, so it can be hard to accept how much we are a product of the society that we live in and that we are not nearly so purposefully at the helm of our lives as we might imagine. The term "free will" isn't quite the right one when talking about what goes on in conscious decision making and what happens at deeper and more subtle levels, however. It makes it sound like I'm saying that we are robots run by someone else, and that isn't what I mean at all.
Cognitive scientist George Lakoff says this:
"All thought is physical, carried out by neural circuitry. No thought just floats in midair. Research over the past four decades has provided insight into how neural circuitry carries out thought that is below the level of consciousness.
Only a tiny amount of our thought is conscious. A typical estimate is about 2 percent, with about 98 percent of thought unconscious.
Moral worldviews, like most deep ways of understanding the world, are typically unconscious. The more that a neural “idea-circuit” is used, the stronger it gets—and may eventually become permanent, effectively “hard-wired.” Hence, most of what we will be discussing in this book occurs at the neural level and is likely to be unconscious. Unconscious thought is studied in the field of cognitive science.
We know from experiments that conscious perception is not immediate. To recognize a visual input, a sound, or a touch input you have to have in your brain neural circuitry that is able to recognize it—that fits it. What if your sense input doesn’t fit what is in your brain? Your brain changes it, if possible, to make it fit.
They (most people) implicitly learned a worldview about reason itself, a worldview that is at odds with the scientific facts from the cognitive and brain sciences. They learned a centuries old theory of rationality that says that thought is conscious (when it is mostly unconscious), that it works by logic (it actually works by embodied primitives, frames, conceptual metaphor, and conceptual integration), that all people have the same logic (which is supposed to be what makes us rational animals)."
So, based on the above explanation about how our cognitive processes actually work, and the fact that our social structures for the past 6-9k years have been highly stratified dominance-based hierarchies which continually justify the rightness of themselves, most white people do carry implicit beliefs about "the correct order of things" which puts blacks and other non-whites into a lower pecking order and assigns stories to them around their intelligence, hygiene, sexuality, work ethic, etc., which come out of the collective unconscious. Whether they realize that is happening or not, it is taking place, sometimes in direct contravention to conscious beliefs about equality.
The results of that contribute to upholding a system that does not treat blacks and others as equals. Is that on par with calling someone racial slurs, treating them with overt disrespect, or burning a cross on their lawn? Probably not, but it still contributes to a world that is rife with disempowering racial overtones and leads to all sorts of pain and disempowerment for those who suffer at its hands.
Part of the hierarchy is class/wealth related, but middle class (and wealthy) blacks still contend with things on a daily basis that even the poorest whites never face. That's what the term privilege refers to.
“Privilege, simply put, is societally granted, unearned advantages accorded to some people and not others. Generally, when we talk about privilege, we are referring to systemic or structural advantages that impact people based on identity factors such as race, gender, sex, religion, nationality, disability, sexuality, class, and body type. We might also include level of education and other factors of social capital under the umbrella of privilege.
Privilege is inextricably linked to oppression, because, while systems, social norms, and biases are advantages for some people, there are others who are disadvantaged by those same systems, norms, and biases."
Your analogies about calling an obese person fatso, etc. are off-target because the terms you used carry with them pejorative judgments, rather than simply naming the situation. Because being racist is (at last) considered to be an undesirable thing to be by most people, it does have an element of pejorative judgment as well, but it's still not the same thing. It's naming the dynamic that is in play, and although I agree that it may push many people away from necessary discussions on this topic, because it feels inflammatory, it is probably, strictly speaking, quite accurate. So, a headline stating that all white people are racists is meant to grab your attention so that you will read about why that is or isn't true. The intention is to get you, the reader, to better understand how, despite no malicious intent, you almost certainly are contributing to disempowering beliefs and structures that lead to racism outcomes. And, some people will never get past the part that feels insulting to read more. Which is why I never use terms like that, because I'm more interested in actual conversations.
You've said that joining forces would make more sense, but in a dominance-based hierarchy, there is no win-win. It's all a zero-sum construct and in order for one person or one group to win, another has to lose. That's why there is so much rhetoric out there now about all the things that straight white men are losing when others who are not that gain some ground. Those men aren't actually losing anything by others gaining rights, but it feels like that to them due to the social system. So, until we move towards a less stratified, less dog-eat-dog and might-makes-right culture, the cooperation you are advocating is unlikely to take place.
The popularity of Donald Trump is overwhelmingly about bringing back this "everyone knows their place" stratification of the 1950s. And it has massive appeal, particularly for less well off, less educated whites, who don't want to lose their place in the hierarchy to others. They may not be the apex of elites, but at least they are close. White women vote for the interests of the men in their lives like no other demographic of women for the same reasons - to maintain a higher position in the hierarchy by proxy.
Resistance to this erosion of the traditional strata of power may well not always be about overt racism or sexism but is often simply a disquiet with the social changes that a challenge to the known and expected hierarchy engenders. It’s a disruption of the social order, and Donald Trump represents bringing that social order back, which is why he is seen as a savior by those who most value the patriarchal dominance hierarchy.
I'd apologize for giving you so much reading, but since I've already researched, thought about, and expressed my perspectives, it only makes sense to not have to reiterate that, and instead, to refer you to those stories, already written.