Just a point on the cheap shipping thing. Most of this is actually because China quotes postage on weight and USPS (and most of Europe) is a tiered system on volume/weight.
A fine example of a piece of shit here. Both packages 80g:
Package 1 ... 35.3 x 25 x 2.5 .... £0.86 second class
Package 2 .... 35.3 x 25 x 2.6 ... £2.90 second class, only 3.4x the price for an extra mm.
China Post ... same amount
You have no idea the arguments I have got into in our local post offices above the extra millimeter here and there and because their own staff don't understand the tiering system or purposely want to charge you more.
I argue that postal services are trying to protect their monopolised rip off price tier system rather than the customers and Trump is using this as a good soundbite for some China hate.
National postal services used to be a bastion of communications purely by scale and monopoly but that isn't true now. They're declining because other private companies such as couriers and even Amazon etc aren't getting screwed for that tiering. It's economically viable to actually take them on at their own game now and for that they will adapt or die. This is the wiggling stage before the death gasps.