Pigface feel free to misled those fantastic Ross Kemp Tough Cops big crime documentaries on Sky that fill in for the fact they have no programs of interest..
it's not that favellas are no go zones for the police, South American police forces are nothing like our boys in blue other than sharing a name, in some cases they are simply the tyrannical civilian enforcers of the regime in power for when the government wishes to avoid looking like a military dictatorship, the just application of any actual law to all people is not their mission. They will often be partisan and in the case of the favellas, the politicians often do not really want to waste fairly limited national resources helping them become civilised settlements it is often more about building a managed wall around the outside to control their contact with the section of society the politicians are supported by. If law breaks down so badly in a favella it bothers law enforcement agencies, it is more likely to be bulldozed or set alight than have it's ills addressed.
Many Police in South America once appointed have to pay for their own uniforms which creates a kind of culture that they feel entitled to then take advantage of opportunities to recover that investment as a perk of the job, with an addiction often setting in after taking small bribes the passage to complete corruption is a natural progression. The cost to correct this is often so far out of the reach of the better governments they just get to accept it.
The South Americans just put up with it, for any Brazilian you are as likely to be shot by a Policeman for no reason in Rio as you are on a tube on the London Underground.
