I work at Google. Many of the "official descriptions" of various levels include "size of team" as part of the description. I think, generally, anyone in a middle management position, particularly at a growing company knows that "more people equals more advancement".
But Amazon is too dysfunctional to change.
Do feel free to suggest a better way to compare two managers that doesn't fall into worse situations than "scope".
Measuring scope to evaluate performance is like saying developer who works on most number of tickets/bugs is the highest performer.
We know that's not true and we also know how it can and will be fudged(w.r.t managers its increasing un-necessary headcount).
If we are able to come up with a solution for developers it shouldn't be too difficult for managers too.
I'm only 20% joking here...
it's not like FAANGs are strapped for teams. Managers can just mnage horizontally instead of needing to hire more people to "prove themselves" (especially when the hiring process is absurd these days).