I suspect that ethnic culture has two elements. One of those is a type of sorting algorithm, and the other is an ideal - a sort of mythological vision.
In the first case, culture permits individuals to determine if others are "one of us" or "not one of us". I think every group - not just ethnic - has such behaviors. Those in the "not one of us" category may have a desperate desire to become part of some group or other, but it is largely a hopeless and futile endeavor. The subtle little nuances of language, behavior, and opinion will reveal the interloper. Thus a Boston Brahmin who loves opera will never fit in with a group of NASCAR fans who delight in country-western music - even though both are white, and each represents an element of what might be regarded as white culture. This effect might be superseded if the two individuals were each members of some group that was more important to them than their other affiliations - for example, if both became QPs.
The other type - and this may be what people mean when they refer to culture - is some sort of arrangement that people within the group may agree approaches the ideal.
I'm going to toss out an idea - and I recognize it may be badly flawed - but I offer it as a first attempt that others may be able to improve upon.
I suspect that "white culture" idealizes the late 1950's suburban American family lifestyle. This may connect rather nicely with Pete's view of the shopping mall, since those malls exist within a specific type of environment - the same kind necessary for suburbia. Further, the malls tend to serve suburbia.
Perhaps such television offerings as "Leave it to Beaver" are suitable examples. There was a stable, nuclear family - a relatively small family. The husband made, apparently, a good living and the wife was a full-time homemaker. They gathered at the table for shared meals. They lived in a pleasant house in suburbia. This vision was, of course, never reality for most - but it was a shared aspiration, and as such was a defining vision.
It occurs to me that the ideal will become steadily more popular, and may achieve a certain near-sacred status as the reality becomes more rare, and more out of reach for most. The environment that fostered the growth of suburbia, with all that implies, seems to have changed - and, for that matter, to be changing. The realities of both finance and society have forced both parents into the workplace - and the increased divorce rate makes the stable two-parent home environment less common by the year. All of this will make the myth seem more desirable - and people will fight harder to keep their dream alive.
Of course, Mr. Beck could not say such things. Telling people that their ideals are impossible does not win friends.
What does this imply? I suspect that anyone who offers the chance to hold onto the nostalgic image of yesterday will profit. Thus microwave meals that permit the illusion of a shared home-cooked meal will be popular. And politicians who promise the return of such arrangements will win votes - and, maybe, elections.