https://en.wikipedia.org/wiki/Definitions_of_whiteness_in_th... - many groups that used to be called non-white, are now called white.
You are not putting enough focus on the "American" in the title. The software makes them "sound American", and sound like a specific group of Americans. It doesn't make them "sound white" and sound like a specific group of whites. The concept of whites has no meaning outside of a particular society's definition of it (in this case the US).
And yes, if you're born in the US and grew up there your accent will be closer to your school/general society than your parents, in my experience. If the school isn't high percentage Indian, then you will "sound white [American]".