The ticketing industry experiences an average of ~15% of purchase attempts resulting in failure - for a myriad of reasons. While our batting average is well below that, and we continue to employ new technology and techniques to prevent failed purchases, there will still be an amount of ticket buyers who experience some kind of friction.
You can check the failed attempts against completed orders on the RN Dashboard (via Statistics > Orders), to see if they later were able to complete their purchase – and perhaps contact those who didn't. Users who simply navigated away, or let the timer run out on their purchase, are emailed automatically to finish their purchase later.