Stuff happens.  And it happens in snow, rain, heat and in darkness.  

Oh, that's crazy. Sorry you're having to deal with this, John.

 "not readable by USPS sorting equipment".  That is most likely the problem.  Talk to the Postmaster in your town. 

   If the problem continues, notify your local Congressperson and/or the local news media regarding failed mail delivery.  Be sure to document each occurence.

Maybe you need to take the problem up with your local Post Master.

WOW 
I am sorry this is happening.  

I did not know the address is keyed in by a person ... I thought it was read by a machine. 

I have experience that as well. They are losing money yet providing worse service. 

I've seen this a few times with machine generated ones too.  Or the sorting machines eat the envelope.

It is about time to shut down this outfit, they have been refusing to do their job for far too long.

COVID causes chaos.

A closer look at anything will reveal need for improvement...Lets improve 

John, this was before the virus upheaval but the USPS lost a cable TV bill before the holidays and a self-employed quarterly tax payment to the IRS two years ago.

We did, on occasion, have to walk mail over to the correct address in our neighborhood a couple of years ago, but things seem to have "sorted" itself out on that issue for the present.

The Post Office has a myriad of problems. but had never heard of handwritten envelopes being an issue

Funny, legally when things are sent to us they have been received but when we send them and they go missing it's a different story. 

Gov't agency's such as IRS, SS, DMV, state the only official channel of communication is USPS.  And the security in place is a friction closure on the box by the street.

What's wrong with this picture?