I see that part of this was explained in another comment already, or I would still have been very confused:-).

Right, well... also distrust your own understanding of everything that you read too!:-P Examine from every angle, if that helps, and then let Occam's Razor be your guide.

From my POV, I presumed it was common knowledge that the USA has never had a billion people, even in the past (even before it was the USA). Nor has any nation on earth, excepting China, and India is much worse, at one point projected to be on track to reach 2 billion by... well now I forget, but anyway, those two are well-known to be isolated having BY FAR the largest number of people than have ever existed on planet Earth before now (that we know of, or have even the remotest shred of evidence for or is even thought to have the tiniest likelihood of having been).

Which is kind-of a big deal when combined with issues of e.g. climate change. China may not have handled it perfectly, but at least they tried SOMETHING, with their various child restriction policies, whereas India's stance that is of a more religious nature, very often prohibits any form of birth control (it's more complex than that b/c there is no singular religion or even vague category of one there, yet many of them share that stipulation, including Catholicism and much of Hindu, and portions though by no means all of Buddhism, and some of the more conservative sects of Muslim & Mormon, etc.).