Regarding the ID verification letters, I can't count the number of ID verification letters I've dealt with since April this year.  The only way I've gotten through to them is when I get the message they're too busy, I hang up and redial until I get put on hold, often having two phones calling at once.  If the automated system offers to call you back, don't push anything.. I've had the WRONG line call me back and we had to start all over. The line that called back was the general line to the IRS and the number on the letter is the only one that will be able to verify their identity.  It's taken me anywhere from 30 mins to 3 hours to get someone on the phone.  Once they're on the phone though, it only takes 20 mins.  Make sure the TP is there as well, even if a 2848 is sent in. They ask questions that are prompted by the computer (often personal questions, ie mother's maiden name, father's name, etc), and if you get it wrong or don't know, the process stops and TP has to go to an in person interview at an open (good luck finding one close) IRS office.

We've also started seeing letters come in now for TP who have paid their 2020 taxes, the checks are cashed, with TP SSN, TY and Form# in the memo, saying TP hasn't paid their taxes due and is now charged with penalty and interest. 

I agree with your response on them. It's an absolute mess this year.