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.
Ukraine tried to come up with drones that can fly over 1000 miles. But drones the size of Shaheds just cannot fly that distance without significantly reducing the warhead. To attack things beyond that range Ukraine have used essentially Cessna. Which is much more expensive and visible on radars.
Instead Ukraine came up with an idea of mass producing extremely simple cruise missiles that could fly 2000 miles and deliver up to a ton of explosives with a cost of 100K and make 1000 of them per month. But then it seems Russia was able to discover the production sites and destroy them.
