It’s more accurate to say all plants have always domesticated humans. We came after them, we depend on them to survive, we’re required to consume their waste to live, so we can’t live without them. They, however, have the option of consuming our waste to live, but are perfectly capable of living without us, and will likely continue to do so after we’re extinct.

Also, a very different climate and soil.

It’s pretty simple, really. Rice doesn’t grow everywhere.