Most problems in IT are reproducible.
When my computer freezes up, I certainly cannot troubleshoot it and if I shut it down and take it in, I doubt they will find it as the next turn on it works as usual. The problems that can be replicated on demand gets solved and corrected though.
Some reports do just that with these cars. Person was able to shut the engine down, get to the curb. A restart worked and everything worked just fine. Dealer cannot find a code to investigate. Not much to troubleshoot on.
