While headlines tend to focus on falling clearance rates in large liberal cities, the decline occurred nationwide in both red and blue cities, counties and states. The violent crime clearance rate, for example, fell considerably between 2019 to 2022 in big cities, which tend to be led by Democrats, as well as in small cities and suburban and rural counties, which tend to be led by Republicans.
OK - you’re right that the entire role of the police is to protect the propertied interests of this world.
However, that is accomplished through the systemic abuse of race as well as class. The people who choose to become police are filtered by a determination to enforce policies which are at their core racist. Even the police who are themselves non-white are often the most violent against other non-white citizens.