Why do southeast asian farmers continue to practice slash-and-burn agriculture and shifting cultivation?

For all the technology coming out of China today, its rural community is still very primitive. Farmers in the Western World have found ways to scientifically improve their growing techniques. Crop rotations allow for nutrient rich plants to regenerate the soil every other year. Also letting a field go fallow one years allows for recovery of soil. There are many other ways the West is improving their crops and educating new farmers in agriculture science. However, southeast Asian farmers to do not have access to this technology or sometimes computers/internet. They are using the same techniques that they have for over a thousand years. Until education is available for them or they are taught different they will continue to use the same techniques taught by their father. Even to the detriment of their land.