The main reason for the low death rates is the lock-down/quarantine in place. India did this very quickly and very comprehensively. I would never have believed that such a lock-down would be followed and enforced in India if i were not living through it. It would be interesting to see how quickly the slope changes once the lock-down is lifted.
Other maybe contributing factors are; Sunlight & UV exposure, High Humidity, a healthy younger population, a better immune system (hygiene hypothesis) etc.
Simply said, the "Developed Western Nations" dropped the ball on recognizing the threat and putting in counter-measures and are now paying the price.