The problem is multi-faceted and money explains most of it. The fact that wealth is associated with racial prejudice is tangential.

1) In the USA there is very little concern for local elections compared to say, the presidency. Most people don't even know who their local elected officials are, and most don't show up to vote in elections that only concern local issues. The only people who participate in local politics are those who have a business interest in influencing local political offices.

2) Yes, a lot of this can be studied with geo data, from both sides of the coin! From the standpoint of the police, maintaining a presence in multiple areas of a city is a matter of time and distance. How long does it take a police car to go from the dispatch location to the scene of a reported crime? From the standpoint of a criminal who is robbing houses, there's a consideration of "how long is it going to take police to get here" if they see that police have no presence in an area outside of the times when a crime is reported. You can also see disproportionate enforcement of criminal laws based on property location. A lot of people don't want to see house prices negatively affected by crime statistics in wealthy areas. When a kid from an affluent part of a city gets caught with illegal drugs, for example, you won't see a large police presence in the neighborhood showing up to investigate. More police means more reports, and reports become statistics, which then in turn negatively affect property values. On the other hand if a poor kid from an apartment in a poor neighborhood gets caught with illegal drugs, the police will happily go there and harass adjacent residences, cars, neighbors, and for lack of a better word turn it into a fishing trip to try and find more petty crimes to charge more people with.

3) Local tax revenue in the USA is mostly from two sources: retail sales taxes collected at the point of sale in stores, and yearly taxes on real estate. A lot of retail sales tax was lost when people began shopping online more than shopping in stores in the past ten years. Most larger online stores now collect and pay local sales taxes (like Amazon) but they did not do so initially, it has only recently been required of them to do so. Prior to changes in local sales tax laws, the responsibility to pay sales tax ultimately fell on the customer rather than the store. Due to that, the reliance on property taxes was even more prevalent than it is now. (1)

4) There is no profit in jailing criminals. There is profit in releasing criminals after charging them fines instead of sending them to jail. Again, for the purpose of maximizing government revenue, there have been efforts to jail fewer non-violent criminals and instead charge them fines and let them go. This is especially the case when there are quite literally financial services built upon paying bail and fines in the USA. Lets say a burglar is arrested robbing a house. It might take 6 months to a year to give him a trial, so unless he has some sort of demonstrable violent criminal history a local judge will simply charge him a bail fee and let him go. Presumably he can't pay the fee, so there are local bail loan services in the USA that, for typically 10% of the amount of the bail, will assume the risk of the burglar not showing up for his trial for him. So the burglar won't have to pay the 5,000 dollars bail he was assessed, he will only have to pay the bail bond company 500 dollars. (2)

(1) Property taxes are not entirely objective. In most places in the USA, people pay property taxes based on appraised value, not on actual realized gains or losses. For instance, if you buy a house, in the first year after the sale you will be charged property tax based on the price you paid for the house, but in subsequent years the local government will compare your houses to sales of similar houses in your neighborhood. If prices rise, they will charge you more based on the assumption that your house has increased in value.

(2) For the most part local judges are elected, not appointed, so they can be bribed with campaign contributions from bail bond companies who don't want those judges to compel them to pay for accused criminals who don't show up for trials.