this selection contains the answer to your question: all those cuisines's recipes use few ingredients in a lot of variations and have preparations that can easily sit waiting for a customer.

it's harder to find restaurants or other places with large or daily menus that can sustain a structured delivery chain as primary income source, maybe they can support the more unstructured uber food aproach but usually that's it. exceptions apply, but parent listed a good deal of causes why this is capital inefficient.

these startups are trying to create a "microcatering" market, which is radically different.