Because the fields are not burnt. The harvesters, that no individual farmer can afford cut the cane and leaves.
It is not a simple as using cane cutting machines as if you do that you strip a major source of income from local workers who can earn between 4 and 8 times the minimum daily wage by cutting cane. So then you concentrate the income into fewer and fewer hands.
Burning cane is quite frightening when viewed from only 10 metres from the driveway and immediately beside the trees on our land.