However, the "last resort" comment I made was a guess to their reasoning - it wasn't an authoritative explanation. My core point is that Amazon seems to think they can do the same, or about the same, or an acceptable amount less with fewer people. If that's the case, then from their perspective, they're overpaying on labor. That's it.
Beyond that, I agree with your larger point, with an asterisk on "overpaying", as I do think an American company should have an incentive to prevent laying off workers just to refill them with offshoring and hiring H1Bs, especially at Amazon's scale of profitability.
There's empathy involved in the revulsion toward this kind of process. Please take time to consider that not everyone fired is a $300k/year rockstar programmer who can just as easily walk over to Meta or Google for a job. I know of people who have uprooted their lives and work under the idea that if they do a good job they'll stay on, when in fact the reality is more like gambling and they could be fired at any point.