The UPU rates are negotiated. Presumably, there were reasons why we negotiated such low rates. I know I read about those reasons somewhere, but don't recall the details.
Personally, I'm OK with Chinese shippers paying competitive rates to send their products through the US mail. I'll miss those $3 items that come from China, but I always felt it wasn't really fair. Then again, there are larger international issues in play, it never was about me.