Of course they should. If a cop makes a dumb move and the city gets sued then mayor should not be held accountable. However, if the mayor ignores police corruption, then I would love them to serve a prison sentence. They have the power, they must use it.
President should be responsible for things he can change, in US a president doesn't really have power to change everything as there are other parts of the government which are involved in decision making.
Any person in a position of power who can CHANGE policies or remove people and doesn't do so, which leads to further incidents and corruption that affect the population should be held accountable.
This will never happen, as powerful people don't want this.