Why not "Love Thy Neighbour as Thyself" ?

Walking down the street yesterday night, I came across an inter-family brawl staged right on the street - it involved two families who lived at 'Care of Street, Opposite Petrol Bunk'... It affected me deeply to see such poor families, living right there on the street, and, in the midst of it all, fighting wildly, mouthing foul words and heaping curses upon one another, darkening the atmosphere with so much ill-will. It was unbelievable and highly disturbing to see such uncontrollable rage and undisguised hatred emanating from a single person... It was very hard for me to digest the sight in front of me and come to terms with reality, as I lowered my head a bit and walked on, quickening my pace.
Why dont people see the fact that life is immensely simple if you let it be ? If people were affable towards everyone and doled out the same treatment to the passer-by on the road and the sister at home, the world will be lots better... If people treated one another with affection born out of humaneness and brotherliness, why would there be family quarrels ? Why would neighbours fight over silly things like whose garbage goes where ? Why would friends disagree over trifles and alientate themselves from each other ? Why would states squabble over the 100th ounce of water that flowed over and quenched one poor man's thirst ? Why would nations wage expensive bloody wars over issues of power ?
Why do humans have to make life complex when, by living it the simple way, life could have been made so much more productive and the world - a much better place to live in... Why ?