Starting Place

I will admit that I am bitter about the ruling that the police are under no obligation to actually do what most of us expect them to do.

Maybe that's where this conversation should start.

What do I, the citizen, expect of the police/sheriff/law enforcement?

First thing I want to make clear.  Law enforcement agencies in the USA are, and must be, the creation of the citizenry.  This may not be true of other nations, but it's certainly true of the US.

The US was supposed to be a bottom-up entity and that was supposed to be at every level on down.

Ironically it's a Brit who coined the core of this for us, and long after the founding.

To maintain at all times a relationship with the public that gives reality to the historic tradition that the police are the public and that the public are the police, the police being only members of the public who are paid to give full-time attention to duties which are incumbent on every citizen in the interests of community welfare and existence.
--Policing Principles #7

In how many places are the public now forbidden by law from assuming their, rightful, duty?

There's a Libertarian concept that applies to the police, because the police are a creation of and employees of The People.

"If it is illegal, immoral or unethical for me to do something, it is likewise illegal, immoral or unethical to hire someone else to do it for me."

Because law enforcement is a delegation of civic power to these full time employees, it means the power comes from The People.  Delegate is not the same word as abdicate.  We did not abdicate this power, we delegated it.

A founding principle of The USA is that the government cannot have any powers that its citizens don't have as individuals.

Why would I delegate my arrest power to an employee of The State?  That employee might be better at it.  That doesn't mean I no longer possess that power.