That's your one job. Ship me the thing in new condition, and you can't even do that. How much is that even saving them on packaging? A nickel? It's disrespectful and greedy, and it's a sign of how awful they really are. You can sell things cheap and be efficient without being trashy.
They don't seem to be damaged in transit, usually it looks like they have been dropped or badly stored.
I always price check Amazon too, quite often it is not the cheapest, and you can get caught out on shipping costs as you say.
How do you lose a page from inside of a box/envelope?
Often, in any case, the damage is more than cosmetic. A paperback book that has been badly creased is more difficult to read than one that's in good condition.
Caring about the condition of books is not a strange idiosyncrasy. There's a clear stratification in the price of the book market as you descend from new to very good to acceptable condition - because buyers generally care.
I'll never forget lending one of the few books I bothered to keep physically to my wife who immediately trying to crack the spine on it to have it open the way she was used to.
The majority of the books I read are digital, though, and have been since PDAs were invented.
There are other problems: 1) Search is just terrible. Often I have to search in Google to find the product I'm looking for at Amazon. The "other people bought/looked at these items" functionality which partially made up for bad search has been pushed out in favor of sponsored products (i.e. ads).
2) Shipping is only fast and cheap if you get Prime, which basically means paying for your shipping in advance and buying constantly at Amazon to amortize your initial investment.
3) Because Amazon no longer actually controls its own catalog, duplicate listings, misleading listings, merged listings that amalgamate multiple different editions of the same book, etc. abound. e.g. search for "Norton Anthology of English Literature". Instead of a neatly sorted list by volume/edition/condition, you get a whole mess of duplicate/overlapping listings, and also misleading garbage like this (shows 3 books but you only get 1 of them): https://www.amazon.com/Norton-Anthology-English-Literature-P....
I'm shifting towards just using Amazon as a 'wishlist' shopping cart and then finding the actual thing to buy elsewhere.