I'm curious about your experience as I had a similar impression before dealing with disputes on a large scale, but since actually fighting them with detailed evidence have won ~80% of them. This is true of order not received, claiming the entire transaction was fraudulent etc. With that being said my business is a digital service so that may be the reason for our different experiences.

What kind of dispute claims do most of your customers make, and what kind of evidence do you provide besides USPS tracking?