The Civil Rights Act of 1964 and Great Society legislation only happened because working- and middle- whites felt comfortable with their economic security.[1][2] The loss of well-paying blue collar industrial jobs may have been partly compensated with cheap domestic goods.[3] But nothing has compensated for the loss of jobs that one could reasonably expect to last for decades, if not for one's entire working life. You're not going to give on cultural issues if you feel that you're losing on the economic front. Quite the contrary, you're going to become extremely defensive and even cynical.

I'm not excusing racism and prejudice. Quite the opposite--I'm saying that it never left, its expression in popular politics only temporarily diminished.

[1] It helped that the poster children for Great Society legislation were, literally, white Appalachian children.

[2] I'm sure the same could be said for immigration in the U.K. It was tolerated or even affirmed by a working class who felt economically secure. Once they felt threatened economically by immigration, and as memories of the Empire faded along with a sense of intrinsic superiority, relatively dormant ethnic animus returned to the fore.

[3] As conservatives infamously argued during the 2016 election; that quality of life has remained undiminished or has even improved, notwithstanding stagnant wages, by pointing to A/C and refrigerator ownership rates. That's true to an extent but largely irrelevant to how people perceive equity and fairness.

When you hear a person talk about something normal, it is reassuring. When you can't understand a word they say, it is threatening. They could be doing something hostile. You might say that logically this doesn't make sense, but that doesn't change the reality. Other languages are exclusionary.

Some of these cultures come with extremely unenlightened views about anybody who isn't a straight male. It's dishonest to deny this.

Your "nice simple little solution - more taxes, more redistribution" isn't a solution even for poverty. Even in those cases when people are poor, the Brexit/Trump people don't want your handouts. They want to be useful, supporting themselves as independently as possible. They want to earn and own. They want cars and detached houses, without any sort of lease, and often they want to do their own repairs. These people don't want to be treated like children, pets, or livestock. They want to be fully in control of their own household, without government interference. Without the need to beg for government help, they want to be able to defend against intruders.

An interesting thing about the cultural war is that the Brexit/Trump people, especially the Trump people, have nowhere else to go. If they lose, their culture is wiped from the Earth. The other side can find their culture all over the world. If they lose, they can head to a typical large city elsewhere in the world.