Couple different classes of customers - utilities are the existing (Electric/Gas/Water meters) and IoT (Sensors, Street Lights, Parking) are the up and coming.
Both of them lend themselves well to mesh networking application, and mesh networks, in which any one of the 5mm+ deployed devices might appear in any one of the 10,000+ network segments, and in which we just want to concatenate the MAC address and Network segment to get a network address (basically SLAAC) - really makes IPv6 a pretty good fit.
Medical devices of some kind? Just guessing.