As topkai22 said, it's to make the author's comparison easy to understand. But this is a chance to mention that ~50 years ago the UK abandoned its old "billion" terminology, which used to be equivalent to a trillion elsewhere (10^12), and adopted the global definition of "billion" as 10^9. I think they called 10^9 a milliard, but I've never seen it in use. For a long time after the change, you'd see English written for an international audience using a more drawn-out version of large numbers (a "million million" for example) sort of the same way we have metric next to imperial these days.
That's not what's happening here, but it's interesting.
Fun fact about long scale billion (short scale trillion): it stands for bi-million because it’s a million millions. Trillion is the same with a tri-million being a million billions.
That's cool to know. Vaguely related: I've been studying a little bit of Mandarin recently and have had trouble with their system of describing larger numbers that doesn't follow the Western groups-of-three system. For example, 万 means ten thousand, but it's actually "one of a thing described by a word representing 10^4," and you wouldn't say 十千 which literally translates to "ten of a thing described by a word representing 10^3." It's surprisingly hard to regurgitate the right labels when your brain is used to thinking in terms of 10^3, 10^6, 10^9, etc. They're all different, internally consistent systems, and as far as I can tell nothing makes one better than the rest -- except for one's own familiarity with it.
Edit: I guess you meant global as far as the English language is concerned only, ignoring the equivalent words in other languages. But even that would be wrong, as apparently Australia adopted the American usage after the UK.
In any case, it's interesting that the US diverged from the European use following the French (who since then went back to the original meaning of billion).
I'm definitely not in the world of finance, but in day to day conversation, I have to stop to think what one hundred sixty thousand million means. If I hear one hundred sixty billion, then I immediately understand. Even if I had previously heard five million then heard one hundred sixty billion, it is obvious that billion is 1000x a million which clearly makes it a bigger number. This is what I meant by unnatural.
Verbal conversation gains the context of audible emphasis on the difference. Rhetorically, you are able to say "Waymo has revenue of 5 million dollars, while Google has 160 BILLION dollars." (imagine the all caps being dramatically stated, possibly a la Dr Evil in Austin Powers).
In writing you can't do that as easily or effectively, so I think keeping the abbreviated units the same is effective writing.
In fact stating income in thousand millions is exactly how financial statements are formatted. In alphabet's 10k (at https://www.sec.gov/Archives/edgar/data/1652044/000165204419...) there is a table showing that the google segment had $136,224M in revenue, while "all other bets" had a total revenue of $595M. I suspect that the SEC would have some stern words for alphabet if they expressed on measure in billions and one in millions...
Why the decision to write $160,000M vs $160B? Was it so the same as the previous $5M number? Even still, it seems unnatural to me.