I believe your point that UPU rates from China are still lower than USPS domestic. I just haven't paid much attention, and I don't know what Shein/Temu deliveries look like. But my point is that at least recent Aliexpress shipments seem to be completely independent of USPS, at least for my deliveries (I've seen comments from other people that got their last mile Aliexpress Choice via USPS, but I think that was still domestic postage). So even if there are still ways of saving using international mail, the subsidy is close enough that commercial operations are still competitive for some packages.
My point about UPS/Fedex is I do not think large retailers are paying anywhere near the published UPS/Fedex rates. I assume that one of the reasons they can get such bulk discounts is from tightly integrating with UPS/Fedex operations such that UPS/Fedex receive whole trailers already sorted per-destination-distribution-center, etc. And I assume anywhere getting such a deal is contractually prohibited from making their actual rates known.
Why do I think this? From what I've seen businesses like Target/Walmart/HomeDepot/Amazon seem very unconcerned with shipping many small packages from different warehouses. This isn't them indulging the occasional shopper who makes a small order (hoping to make the cost up later), but them being actively content with shipping one or two items per package. If they were paying the steep per-package rates that retail and small businesses pay, we'd see a lot more pre-shipment consolidation.
My point about UPS/Fedex is I do not think large retailers are paying anywhere near the published UPS/Fedex rates. I assume that one of the reasons they can get such bulk discounts is from tightly integrating with UPS/Fedex operations such that UPS/Fedex receive whole trailers already sorted per-destination-distribution-center, etc. And I assume anywhere getting such a deal is contractually prohibited from making their actual rates known.
Why do I think this? From what I've seen businesses like Target/Walmart/HomeDepot/Amazon seem very unconcerned with shipping many small packages from different warehouses. This isn't them indulging the occasional shopper who makes a small order (hoping to make the cost up later), but them being actively content with shipping one or two items per package. If they were paying the steep per-package rates that retail and small businesses pay, we'd see a lot more pre-shipment consolidation.