From personal experience, it was not long ago that you could buy stuff on eBay from sellers in China for a few dollars and have it delivered to you with free shipping. That required subsidies from the government of China and with the cooperation of the US government. Basically, US sellers of similar items in the US were shut out of the market.
Now the free shipping thing seems to have disappeared, but China sellers are now offering shipping to the US for much less that it would cost a seller in the US to ship to China.
I believe China still subsidizes shipping, just not to the extent that it used to.