Anecdotally, most people I know don't go out of their way to interact with police, so when police come into the picture it's usually not for something good. Further, because it's not for something good, that makes the situation more tense and incongruous between parties involved. People try to actively avoid police and not deal with them. If most interactions are negative, this makes conflict resolution difficult if the sentiment towards one party is inherently distasteful. This might be a bad metaphor, but it's kinda like how people don't use customer service when they don't have a problem. If police want to be guardians of a community, it requires putting in time to listen to and understand the community, and it also requires the community be cognizant of their interactions with police. Like with customer service for any party involved, being shitty usually doesn't make things go smoother.

With that being said, I think police could do a better job of being helpful and approachable. In the times police are actually needed, such as a car accident or something being stolen, adding a bit more effort would go towards establishing a better impression among the public. Further, changing the structure of police incentives could also help, where they should be rewarded and recognized for the positive outcomes created in the community, and not the number of tickets written to bring $X dollars into the station.