It is vastly more complicated to find targets at 1500 miles than at 20. So drones are effective at destroying big stationary civilian infrastructure and much less at long distance strikes at military targets. Russia's inability to destroy Ukrainian aviation is a good example.
But then with solar and batteries civilian infrastructure becomes much more resilient against drone strikes.
> It is vastly more complicated to find targets at 1500 miles than at 20.
It's true but they are so cheap that launching a whole bunch and/or improving them incrementally is possible. Yeah they are for stationary targets mostly, for sure. And of course their sounds and relatively low speed does make them somewhat easier to shoot down with short range AA guns and can have automated acoustic early warning system (it's like a flying lawnmower or chainsaw).
At a certain distance, I'd contend all infrastructure is big and static. Our energy comes from large facilities, without these facilities continent scale infrastructure will grind to a halt at 1500 miles. Rail, power lines, warehouses, factories and trucks are all relatively static. It's not unreasonable to expend a Shahed type drone on a simple semi-truck parked overnight from nearly a continent away. There are only 3 million semi-trucks in the entire US, and I'd be shocked if the country could run without them.