When you have to be extremely noise/fault tolerant (e.g. you can literally remove half a brain and still function normally [1]), you over-design and over-engineer the system with massive redundancies everywhere. We don't know how much information is actually encoded in these trillions of low precision synapses. Our best deep learning models tend to be very over-parametrized, and are highly compressible. A CPU is nowhere as fault tolerant but it does not have to be, because modern solid state electronics is extremely reliable (and has much wider ranges of operating conditions than human brains).
“It takes a radiation dose of about 5 Sv to cause death to most people. Diodes and computer chips will show very little functional detriment up to about 50 to 100 Sv“.
It's to note that "little functional detriment" contributes to a catastrophic failure in a digital system. A flip of a single bit can fell the thing you're trying to operate. Humans respond with much more delay and can usually complete most any mission, even if they die of complications later.
