Before
Crime
Poverty is one of the obvious causes of crime. When people don't have the means to support themselves and their families, many will turn to crime to try and make ends meet. Instead of tackling the root causes of crime we convince ourselves that the answer is to increase the size of our police force so that criminals can be caught.
Militarization
Since 9/11 and with the creation of government agencies such as Homeland Security, there has been a subtle and gradual move towards increasing the firepower of our police, so we see less and less police walking in our communities and more and more combat gear, armed vehicles, and more threatening postures displayed by the police. Incidents that would have been simple arrests in the past are now dealt with by shooting and often killing minor offenders.
Abuse of Power and Corruption
While there are of course many decent law-abiding members of our police there are also many cases of obvious corruption and abuse of power. From simple "turn the other cheek" incidents when the police or people they know are involved in crime and nothing happens to them, to blatant miscarriages of justice, the police are simply not treated the same as ordinary citizens.
Size
When crime rates are high, we react by increasing the size of our police force, but rarely do we reduce the number if it is excessive. There are small towns all across the country with police stations full of paper-pushing cops, and there is usually an outcry if police are asked to reduce their numbers because of cuts.
After
In Nutopia communities there is no need for a police force for a number of reasons:
No significant crime
No vehicles
The comprehensive public transportation system means that there are no roads, no vehicles, no bad drivers, and no drunk drivers or texting drivers . Car accidents, traffic cops, police chases, and speeding offenses, are all things of the past.
No binge drinking or alcohol related offenses
No illegal drugs
No weapons
Citizens of Nutopia do not possess any weapons, ammunition, or explosives.
The Nutopia community does have citizens who have learnt the skills for resolving disputes between people, and restraining people who are a danger to themselves or others, and these people are called upon as needed. But these people are ordinary people who also have other skills which they use to contribute to the community as does everybody else so there is no concept of a dedicated police force.