Because a human putting 5 in the field for 1+3 is an isolated mistake, but the machine doing it is the result of a deterministic process that is likely to occur

Because a human putting 5 in the field for 1+3 is an isolated mistake, but the machine doing it is the result of a deterministic process that is likely to occur much the same way over and over again. In other words, no, we don't ignore MCAS causing the plane to go into a stall under some isolated circumstance just because humans also put planes into stall.