Several academic studies now show that LoRaWAN collision rates can exceed 80% for networks being used.
in-depths reads:
- A Study of LoRa: Long Range & Low Power Networks for the Internet of Things http://www.mdpi.com/1424-8220/16/9/1466/pdf
2. Understanding the limits of LORAWAN
http://128.84.21.199/pdf/1607.08011v1.pdf