The last article addressed some advertising that the USPS has done. What they may have spent does not compare to what other carriers have spent on their advertising such as UPS and FedEx. The USPS is still governed by Congress but is independently financially funded by the sale of stamps and services.
So go to your post office, use the services offered and quit referring to all the advertising that goes through the mail as junk mail. It is now the bread and butter of the USPS. Contact your Congress person now.