They may do more investigative and arrest work but the they "almost" never stop crime is untrue.
I suppose you can argue what constitutes "almost" but the truth is VERY few crimes are stopped by law enforcement officers. They may be investigated and the perpetrators brought to face justice, and law enforcement may set up stings to catch criminals in the act of some transactional or otherwise
malum prohibitum offense, which might constitute stopping a
series of crimes, but the situation of a police officer being in in the presence of a criminal in the act of his felonious crime, and being able to halt that crime in progress is exceedingly rare.
We have quite a few current and former officers as members (and Staff) here who we can query to ask how often they stopped a crime in progress.
I never said any such thing. If you claim it wrong to use deadly force to stop robbery because life is worth more than things then a rational conclusion cops shouldn't try to stop the thief either because they could get killed in doing so.
Police officers are hired by society, as agents of the government, to bring law-breakers to justice. (Again, not really to "stop a thief" as that rarely ... almost
never ... happens.) That is a function of keeping the peace. We ask those officers to take on heightened risk, and we give them greatly expanded authority, and physical and legal protection far beyond anything a private citizen may claim, to do so. We also give them as much means as possible (through the force continuum/pyramid (including less-lethal devices), extensive backup/support, the official personae as a person of authority, the authority to respond with arrest powers and even force after the fact, etc) to apprehend those suspected of breaking the law in such a way as to greatly minimize the probability of either the officer's -- or the SUSPECT's -- death.
And we do so in order to bring them to society's justice -- not that of a private individual. Remember that if someone assaults or kills another person, the harmed person or the estate of the deceased is NOT party to the criminal trial. The trial will be THE STATE -vs.- the accused. This is a higher cause than any one person's vengeance or restitution. It is
society's interests being enforced and thus being deemed of appropriate gravity to send a public servant into harm's way.
(Also note, that no matter WHAT was stolen or destroyed or violated, when a CIVIL trail happens, that will be the victim's chance to obtain restitution from the accused. And in civil cases, NO ONE's life is ever on the line.)
True, the constitution specifically is written to define the roles of the federal gov't but it was written because it was believed that the rights we have are inherent which is why they were not to be infringed upon. And it in now way implies that only the federal gov't can rob one of liberties.
But it provides no justification for one to take physical retribution or excessive means to prevent a minor offense against you. Regardless of the Constitutional protections which seek to prevent the government from seizing your possessions, such acts between individuals are matters of law, to be decided in court, and the state does have the monopoly on punishment of crime.
Our use of deadly force as private citizens is only just when used to prevent immediate death or serious injury or other life-threatening felonious offenses.
(-- Of course, that's "except in Texas, at night, under certain circumstances." ... which, once more, this situation wasn't.)