I don't think anyone in India thinks farmers are given any unfair advantage. Actually all part of society is screaming to provide help to these people who still dare to farm instead of selling of their lands to real estate mafia even after all the stories of farmer suicides [1]
That may well be; but historically, farms were the perfect vehicle to launder ill-gotten wealth. You claim (on paper, and certified by greasing some palms) that your farm's output was $X*2, when in fact it was $X. Suddenly, the extra $X of money is counted as "agricultural income" and tax free (AFAIK).
[1] http://en.wikipedia.org/wiki/Farmers%27_suicides_in_India