Why do Lebanese schools give so much homework?

This is a world wide problem i still remember when i was in that age my mom use to sit beside us and help us to finish the homework, and regarding the backpack it is a reall punishment but the problem is that by the time if the boy or girl us to carry it by himself or herself the back problems begin and it may conduct a spinal deviations or something. İt is better to carry on a small luggage with wheels. Now i see my neighbours and friends suffering the same problem regarding the homeworks of their sons in the firsts grades, then afther 4th grade they leave this helping to extra cles in the afthernoon. Sometimes i think that the children are lossing their childhood in homeworks and exams and extra clases..and the worse when the reach the puberty they are a reall antisocial guys flying in their science world..they even sometimes forget how to say hi...but that is the cost of global competition!.