Now, I agree with you that if you believe a home kitchen scale is telling the truth, you are a fool. But as an old toolmaker who dabbled in accuracy for a living, displayed digits does not equal accuracy nor even repeatability. And there can be a fair amount of interpretation involved in analog beam scales.

I think it’s just another PPS, (piss poor scale), scale that is neither accurate nor repeatable. And the packaging material weights are rarely included in listed weights. Since packaging can change at any time due to costs.