If USPS is subsidizing international shipping from China by overcharging for domestic shipping, as some here are suggesting they are, how do they successfully compete with UPS and FedEx? Or are UPS and FedEx also subject to the UPU?
The USPS can't increase their domestic prices but there is good indication that they are charging more to offset this. There are complaints in this thread even about the cost of shipping abroad, as international shipping is not regulated like domestic postage rates if I remember right. So the USPS uses outbound international shipments as a cost center to make up for the subsidy to China.
The article states there is a ~$500M subsidy to China through UPU rates.