Indian restaurants thousands of miles apart in the United States often print nearly the same menu. The convergence has traceable causes, and none of them is that these dishes represent Indian cooking as a whole.
The founding kitchens set the template
The restaurant trade that spread through Britain and then North America was built disproportionately by cooks from a few regions, and the dishes that travelled were the ones they knew commercially.
Those dishes were mostly northern, wheat-based and tandoor-centred, which suited diners already familiar with grilled meat and bread.
Later arrivals entering an established trade tended to reproduce the format rather than compete against it with something unfamiliar.
Ingredient supply narrows the options
A menu can only include what a kitchen can source reliably every week. Distributors serving Indian restaurants stock what most of their customers order, which reinforces the existing list.
Regional ingredients with narrow demand are harder to obtain, more expensive and prone to gaps. A dish that cannot be served consistently gets dropped.
The result is a feedback loop where the common menu makes common ingredients cheap and uncommon ones impractical.
The kitchen is built for one system
A tandoor and a base gravy line handle the standard menu efficiently. Dishes outside that system need separate pans, separate timings and separate prep.
Adding them raises labour cost during service, which is exactly when a restaurant has least slack. The economics push towards dishes the existing setup already produces.
Staff hired into the trade are trained on that same system, so the skills available also point in one direction.
Diner expectation closes the circle
Guests arrive expecting particular dishes and read their absence as a gap rather than a choice. A restaurant that omits the familiar names fields the question repeatedly.
Heat levels are handled the same way, offered as a scale so a table with different tolerances can order comfortably from the same page.
Menus therefore grow by addition rather than substitution, which is why they run long and look alike.
Where the pattern is breaking
Restaurants built around a single region have become steadily more common in larger American cities, often opened by people cooking the food of their own home rather than the trade standard.
They tend to run shorter menus, since a focused kitchen does not need to cover every expectation. That shortness is what allows the specificity.
Their spread depends heavily on local supply, which is why they cluster in cities where the ingredient trade is already deep.