Your claim here is basically incorrect.
"Parcel select" is a service for large mailers who deliver packages, in bulk, to multiple post facilities in the US, near to the destination of the package and have the USPS do the "last mile delivery". Does China Post have a fleet of trucks, in the US which moves Chinese packages to a closer US postal delivery facility. I believe not.
Moreover, if China did have such a service, someone, China or the US is subsidizing it since individual shippers in China, not doing any aggregating themselves get a rate equivalent to large shippers in the US who aggregate and must pay the costs of this themselves.
"“Parcel Select” is the registered trademark name for the Postal Service’s economical ground delivery service for packages entered in bulk, including those entered at destination facilities. It is designed for and generally used by large- and medium-sized parcel shippers. Parcel Select mailers pay postage that reflects the degree of work-sharing they do in presorting their parcels and/or drop shipping their pieces at a destination facility located closer to the delivery point. Mailers are responsible for transporting their Parcel Select pieces to a destination bulk mail center (DBMC), destination sectional center facility (DSCF), or a destination delivery unit (DDU) for business and residential delivery."
https://about.usps.com/postal-bulletin/2007/html/pb22219/kit...