Back in the day (a bit before my time) businesses had hold up alarms that rang directly into the radio room and did not have to be relayed to the PD from the alarm company when the alarm was activated. This included some direct hold up alarms we installed in high risk businesses. Several bad guys were smoked due to the quick response times from officers based on this arrangement, including one I saw photos of early on in my career who caught a full load of 00 Buck at close range. I was told there were no longer direct reporting alarms due to politicians worried about the number of bad guys getting killed by police. I don't know if that was the case or if the number of hold up alarms increased to where it was not feasible to have them all report directly. I suspect it was mostly the latter.
My unit (Major Crimes) conducted a fair amount of robbery surveillance in the 7 years I was there but was only involved in one shooting. I do know that if a hold up guy got smoked by a business owner/employee or the police, and it was well reported in the news, armed robberies seemed to slow or actually cease for a bit.