Years ago AA removed the ability to print the ticket receipt from the kiosks (which was necessary because the website only intermittently provides the "single-page" receipt which includes price and ticket number). I got into the habit of having the AAngels print it, always mentioning that the kiosk used to do this (meaning it was added work for them).

Printed receipts are useful as are printed boarding cards, both in IRROPS and also for any after-the-flight questions, including expenses, audits, legal matters, and of course frequent flyer claims.