Ever since I saw that the grocery store near the train station in my city (which is famously one of the worst in the country in terms of crime) had self checkout without even a gate to scan your receipt for a while (they added it now) and has the handheld scanners, I've been assuming that the added theft from either really can't be that bad, or is a result of poor security. Clearly it's worth it for the higher customer throughput for that store, so I kinda doubt it could be that bad especially in safer areas.