https://www.forbes.com/sites/wadeshepard/2017/11/05/how-the-usps-epacket-gives-postal-subsidies-to-chinese-e-commerce-merchants-to-ship-to-the-usa-cheap/#5e153c6140ca
Chinese direct-to-consumer US sales are being bolstered by subsidized shipping that makes it cheaper for businesses in China to ship light products to homes in US than s domestic supplier can send the same package across town. The subsidy partially comes from the US taxpayer and increased rates for US domestic shipping.
With all the trade-war talk, this seems like it would be an easy thing to fix have a positive impact.