ill try and address your points, if not, feel free to repost any questions or comments that go unanswered.
no, we dont want robots enforcing the law, or in any profession where contact with people is the key to a successful career. this, in and of itself, results in at least two serious concerns.
1. not everyone is going to agree with the way an agency or individual officer performs their duties.
2. people make mistakes. but law enforcement officers are judged not by the end result, necessarily, but how the situation appeared at the time to that particular officer, and whether another officer with similar training and experience would reasonably have acted in the same way.
many laws are selectively enforced, ie, the officer is not legally obligated to cite/arrest. most traffic laws and many misdemeanor or lesser crimes fall under this category.
felonies are "shall enforce" laws. i am obligated to make an arrest when a felony has been committed and i have a suspect detained. but there is even some flexibility regarding felony crimes.
everyone is different, and it takes all kinds to make a department successful. you have the officers who are great at pr, officers who love to enforce traffic laws, narco, swat, etc. most find a niche and work within that framework.
some will arrest on all narco violations, regardless of circumstances. some will arrest on the felonies, but not for marijuana.
there are statistic driven agencies, and there are service oriented agencies. LAPD is stat driven, Fullerton PD is service oriented.
stat driven agencies look at the number of arrests in various categories (including citations), and report their effectivness in that manner. service driven agencies tend to look at stats as a secondary priority, and many calls are pr contacts. they will take reports and sometimes conduct investigations that another agency will not have the manpower to complete; missing weather vanes, damaged lawn gnomes, etc. it depends on the clientele, the number of officers per citizen, and the level of crimes occurring most often within a reporting district.
NYPD has over 20,000 officers. as i understand, they are a combination of service and enforcement. LAPD has under 9000 officers, and one of the most densely populated cities in the country. roughly 15 million people live within their jurisdiction. there is no way LAPD could provide the same type of service as NYPD. simply not enough personnel.
if every law was always enforced, society would not collapse. that's a bit over dramatic. but the jails would be full, the courts will be backlogged, and ultimately that agency would have to start to make different choices about how the service their community. in los angeles, the jails are already full and the courts backlogged. but within the city of l.a., are many of the most violent places in the country. nearly all weapons laws are enforced, without predjudice.
i am given quite a bit of discretion regarding enforcement. it is highly unlikely i would enforce a lower level felony on an elementary school student. that same crime commited by a teenager may require prosectution. cirumstances often dictate the outcome and my personal involvement.
in your profession, you are mostly guided by policy, not law. violating policy or procedure is not the same thing as violating a law. if a doctor feels a particular act, or ommission of an act, is not in the best interest of the patient, their moral dilemna becomes whether or not to violate policy or act, as they believe, in the best interest of the patient.
police officers act in this way all the time, but it is not quantifiable, and no one discusses this. people rarely talk of the positive contacts they have had, but would rather rant about the one negative contact they had, or heard about from some third or fourth party.
The fact that something is legal or illegal doesn't make it right or wrong. At one point, slavery was completely legal. Does that mean that law enforcement officers were compelled to enforce it, regardless? Making the law into something static and unmovable is a scary suggestion.
this last section is a bit muddled. you've taken something out of context and attempted to apply it to today. slavery was once legal. it was legal to own another human being and basically treat that person as the owner saw fit. culturally, it was seen differently than we see it today.
there was also little law enforcement to speak of. constables, local sheriff's, and the army enforced many laws. organized law enforcement agencies were few until the late 1800's, even then many were basically mercenary types like the pinkertons.
if a slave ran away, he was property and the owner had the right to have that property returned. in that sense, whoever was responsible was obligated to enforce those laws, to some degree. might we view the hypothetical confederate soldier who helped slaves run away as a hero? today, surely we would. in the mid 19th century, he would likely have been viewed very differently.
is that right or wrong? then, per the laws of the various states, it was right. today, and in other states at that time, it was wrong. but, ultimately, comparing eras in history is a slippery slope. many of our early presidents are still considered great men. but many were slave owners, does that make them any less great? we shouldn't force our values on those who lived hundreds of years ago and expect there to be some congruity and have it be meaningful. but the past has great influence on our laws today and the moral/ethical stance we take regarding such issues.
if something is illegal, it is wrong. if you do something illegal, you are in the wrong. no way around that. whether you agree or not is not relevant as far as any court is concerned. while appropriate in some cases, try not to confuse what is legal and what is moral. the two most often dont mix. the simplest example are traffic violations. most are based on the safety of drivers and pedestrians, but many are not. some seem entirely arbitrary. there is no moral/ethical stance for double parking. there is no moral/ethical stance for failing to stop at a stop sign (in and of itself).
your opinion about any particular law will have no influence on whether it is enforced when you commit the violation.
and laws are updated, eliminated, or added constantly. in that sense they are not static or immovable, but they must be clear, and too much change results in unenforceable laws. language to clarify or include additional violations or exceptions is quite common. this has always been the case. im not sure what you find scary, you need to quantify that last statement.
wow, my longest post ever. hope i have cleared up at least some of your questions and concerns.