No to remove the cap on pricing. USPS was break even from 1970-2006 until the 2006 law that forbid them from raising prices. The business mailers love it though.

Companies are already using the roads, police, fire services (where applicable) and many other government services without paying directly for them. But the taxes! you'll scream - yes exactly!

Standard communication (including addressing) is such a basic, critical function of government that it only makes sense to do it at scale and just fund it with taxes.