While true the tech is not complex, I believe the discrepancy is "how accurate is it and is the data being manipulated to fit a crime" versus "the data is accurate and leading to fair justice outcomes."

Wouldn't "red teaming" ShotSpotter solve for this to see how accurate they are? A team would perform controlled firings in known locations under various auditory scenes with the city's approval, and then request the data from ShotSpotter to see how accurate they are (without revealing you are performing an exercise). ShotSpotter then doesn't have to reveal their methodology, as their data provided from a blind test will reveal the accuracy regardless of how they arrive at conclusions. The system is either accurate or it isn't (with a measured level of confidence), and this can be tested for without ShotSpotter's consent (as long as they continue to provide data to the customer per their contract).