Why are some parcels sent later, but they arrive earlier?

This is how a warehouse properly handle the parcels -- always handle the parcels that come early. But actually it is NOT working easily, especially during the coronavirus pandemic.

It is disappointing when you know that your parcel will have to arrive later, even though it is sent ealier.

Why is this strange thing happening, this is how it works:

Before the coronavirus broke out, the post office workers could handle everything normally, for example, at some sorting facility, there are 10 workers who can handle 500 parcels a day.

After the virus came, 5 workers got infected by the virus and couldn't come to work, so that there are only half workers processing orders, so that they can only handle 250 parcels a day, and the other 250 parcels will be waiting there, and no one knows if they have arrived, neither US nor China knows that parcels have arrived, because the parcels haven't been scanned in the USPS system.

And the next day, when the half workers are going to handle the previous 250 parcels, the next NEW 500 parcels arrive again, and the new parcels block and cover the previous 250 parcels, then they have to handle the latest parcels, before they are able to process the oldest parcels.

New parcels keep coming in, while NO new workers are joining in, then there will be more and more parcels that can NOT be handled in time and stuck inside some corners of the warehouse, UNLESS the new workers join or fewer new parcels come.

That is why this strange thing is happening, your parcel was sent early, but you still haven't received it, and someone else bought things later, but they received the parcel earlier.

We know it is strange and not fair, but USPS is badly suffering from the virus, and they still have very low processing capacity.

Virus will be gone, and everthhing will get back to normal.