They do exist in all sorts of ways, not sure why you believe they don’t. There are even specific groups for each individual flavor of “white” (Irish, Italian, etc.). Typically, groups like this become less active as they become less repressed/disadvantaged (people no longer need to organize for safety or to secure their rights once society broadly accepts them and they are no longer under threat). Irish, for example, were once not regarded as “white”, same for Italians.

It’s the same ignorant bullshit people have been doing for thousands of years, there’s always some sort of out group when people in charge are looking for a scapegoat.