A big part of it is even just the inscrutable failure rate of complex early warning systems composed of software, ground/space based sensors and communications infrastructure
This list of nuclear close calls has 16 elements. Laplace’s law of succession would give a close call a 5.8% of resulting in a nuclear detonation. Again per Laplace’s law, with 16 close calls in (2022-1953), this would imply a (16+1)/(2022-1953+2) = 24% chance of seeing a close call each year. Combining the two forecast gives us 24% of 5.8%, which is 1.4%/year. But earlier warning systems were less robust to accidents and weather phenomena, and by now there is already a history of false alarms caused by non-threatening events, hence why an order of magnitude lower for a baseline year—as in the superforecaster estimates that Luisa Rodríguez references—doesn’t seem crazy.
This list of nuclear close calls has 16 elements. Laplace’s law of succession would give a close call a 5.8% of resulting in a nuclear detonation. Again per Laplace’s law, with 16 close calls in (2022-1953), this would imply a (16+1)/(2022-1953+2) = 24% chance of seeing a close call each year. Combining the two forecast gives us 24% of 5.8%, which is 1.4%/year. But earlier warning systems were less robust to accidents and weather phenomena, and by now there is already a history of false alarms caused by non-threatening events, hence why an order of magnitude lower for a baseline year—as in the superforecaster estimates that Luisa Rodríguez references—doesn’t seem crazy.