Food traditions form a large component of just about every culture, and they evolve over time. But when it comes to American food legacies in particular, there have been some huge changes in the past 50 or so years. Similar to the automation and regulation that have occurred in industrial settings such as the automobile industry, American meals have become increasingly homogenized and standardized in an effort to ensure customers that the look and taste of the food they're served will be as expected.
That being said, it seems a little odd that the Smithsonian would find a place for what's known as a bun gauge in its collection. Not exactly a glamorous artifact, the bun gauge (McDonald's in origin) is used by fast-food workers to measure the correct height and width of a sliced bun, a regular burger, a Big Mac and a Quarter Pounder. Would you like a pickle with that precision?