I've always experiencced that if a package fis through the slot, they'll count it as first-class, essentially 60% of the cost of MM. Just got back from the store that has grocery store employees working the mail counter, and a worker wouldn't even try taking it first class, because he knew it was a book---as if that matters. I asked him to explain why he had to go Media Mail, and he said "Take it up with the post office" and then proceded to overcharge me with these ridiculous Media Mail prices. I'm getting peeved. 

I mailed an audiobook today.  It was bigger than a letter, so it didn't qualify for First Class.  Since it was a recorded book instead of a paper book, it didn't qualify for Media Mail.  I had to pay $6.70 for the Ground Advantage rate.  The postal worker showed me the paperwork that indicated this has been the rule since 2017 but they had just received a reminder memorandum and had to enforce this rule.  Has anyone else had to deal with this?  

Pamela. I have never had that happen. This is what it says on the USPS website:   Media Mail rates are limited to the items listed below: Books (at least 8 pages). Sound recordings and video recordings, such as CDs and DVDs.