I love that the American solution to fire is... fire? We tried putting grown-ups with guns in schools after Columbine, and somehow more guns hasn't solved the violence problem. I don't think putting a cop outside each store will stop theft, especially when wage theft alone represents a larger loss than all larcenies, burglaries, and auto theft combined. [0]
> in the first 24 days of 2015, police in the US fatally shot more people than police did in England and Wales, combined, over the past 24 years [1]
I don't think diordiderot is claiming more cops = better. They're giving one example of how police could stop crime, but one that is self-evidently not scalable. One cop per storefront would cause the number of police to explode, and even then only covers a specific subset of crime (i.e. I think they'd agree with you).
It is a common complaint that the police tend not to prevent crimes but instead just show up afterwards and at best shrug and move on (at worst they do pretty gruesome stuff like sexually harass the victim or shoot the person who called them in). So I'd agree that more police or more guns probably won't cure the causes of crime.