I have no idea and have found it extremely peculiar since none of them seem like they would do drugs, and I think its extremely unlikely that they have all become senile.
Many people and cities have sprinkler systems set on a timer. Unless you have a rain sensor set up as well the sprinkler just goes off at a certain time. That is what you see. I try to turn mine off when I know it is going to rain but sometimes I am out of town. My neighbor took a picture of me watering my lawn in the rain. She though it was hilarious, but my water bill didn’t!
Happens in Darwin all the time during the wet. The sprinklers are on timers as was suggested above. But there is no water shortage in the top end. Each year the whole place floods and then is soaked up when the dry comes until the wet and then it floods all over again.
Think it’s been said but the sprinklers are generally on a timer, but they use what is called gray water. What’s really a hoot is busting the sprinklers so they spray straight up, I had a buddy that used to like to do that, sorry off topic. Yes, the timers, probably go off in a hurricane.