If you work for a company that has an RMA process, they will keep records of everything. From my experience, at my company that I work for, keeps records. Like how the financial department will keep track of every single transaction no matter how little. They will also keep track of items sent back as free replacements.
Sample of what my company keeps records of
-When the RMA number was issued
-When the RMA was received
-What was the RMA issue
-What was done to fix the RMA issue
-Which technician fixed the RMA
-When the RMA was sent back to the customer
People just assume RMAs are stacked in a pile and fixed by a random technician.