Im confuced about something in real life gangs fight each other over control a city but in this game they work together its stupid thats not at all how it is in real life so why do we work together some1 please tell me why this is

Blame SexyBeast

We work together to grow the game, so that everyone has a great experience whilst playing. Wars aren't good for the general flow of the game, as they stop money making, street activity, and halt basically all production until people can begin to rebuild.

In the real life mafia different families often worked together to remove a family that became a danger to them all. In fact it was in the very era in which the game is set when mafia commissions began and it became very dangerous to move on another crew unilaterally. Everything was passed through the commission and was approved if not acted on by the heads of other families before any war. Sure maybe today's street gangs don't work together but that's hardly what is being role played here.

I'm not sure... is that trolling or ... ?

I suggest you read a bit more about mafia history and a bit less about current gang fights. Between the two, I have personally quickly chosen which one is the most stupid.

It became beyond simple alliances in cases, where marriage tightened up these families to strengthen the bonds between them and increase organised crimes hold.  The idea is it is not as simple as street gangs fighting for a few metres of territory which in the real world could easily be worth 30-40k in drugs trade(like demonstrated in empire).

Ive thought myself about that if i was ever a city leader i would experiement with authing two people in the city who hate each other and actually let them fight.

While this might be more RL accurate the game has evolved to see each city as one big family who all get along. And lets not forget that when all was right in the world each city did operate harmoniously with honor and respect to each other.

As much as the occasional inner city skirmish would be true to life it would distrupt the game too much as Ramona mentioned, making progress imposable.