Another possible reason they want to shut down the USPS -- surveillance
Why is the government keeping every piece of data they can get on every single citizen? The simple answer would seem to be: because they can. They have the technical capability and the sheer storage capacity to make massive databases of every phone call, text, email, CCTV footage, every bridge crossing, credit card transaction, etc. They can link your PayPal account to your user names to your ISP to your cell phone number. Track the location of your phone whether you are talking or not but the mail...
Sealed envelopes with messy handwriting. Return addresses could be missing, illegible or inaccurate. They have machines that can look inside of sealed envelopes and scan the written contents of a folded letter layer by layer but that is cumbersome and labor intensive compared to using software to read your texts and emails. Linking the contents of a sealed envelope back to your email, cell phone and credit card records is much more difficult than linking the rest to each other.
Fascists are legendary for their fastidiousness and at this point the post office is like an un-weeded section of their evolving human factory farm.