Whew...that's a tough call. I've been to cultures where cops don't have to carry firearms.  But, the reason they don't is because the public polices themselves, and they simply don't break laws.  We have some nasty, nasty areas here in the U.S...borderline 3rd world stuff.  To ask a cop to go into that situation unarmed might be asking him to commit suicide.  It might be argued that in some areas, the public needs to earn the right to be treated with empty arms and not armed ones.