Yes, because the incident they reference was a mid-PCB-layer chip discovered by govt agencies using X-rays. The findings were presented at a private conference in Virginia. Sources who attended said "they've seen the xray pictures" etc.

I specifically mention non-automatic inspection as automatic one may well not have the "paranoid mode," unlike a human who specifically told to go over every individual square millimetre.

Minimum quantity orders for these servers are typically 10,000.

Even at 1,000, I don't see how humans could reliably detect this.