But surely the locals were upset that they were losing money, not that the money they lost went to city hall. In other words, I doubt they'd be relieved that their money was going to corrupt policeman rather than the city government.

If all the available money for fines was being extorted from drivers by corrupt cops, the city would have to get money another way, or cut services. This would likely upset the people of Ferguson even more.

Another way of looking at it is, what wealthy, safe, clean, productive societies regularly engage in bribery?