Every additional line of code running in supervisor mode represents potential security and reliability risk. By stripping drivers, file systems, and network protocols out of kernel space, microkernel architectures dramatically reduce catastrophic failure vectors.
Industrial software statistics indicate an average of 1 to 5 bugs per 1,000 lines of audited commercial code. In a 30-million-line monolithic operating system, this implies thousands of latent bugs. In a 10,000-line verified microkernel, exhaustive formal verification ensures defect density approaches zero.
ISO 26262 requires 100% MC/DC (Modified Condition/Decision Coverage) testing for ASIL-D software components. Achieving MC/DC on a 30-million-line monolithic kernel is mathematically and economically impossible, while an ultra-lean 10,000-line microkernel can be certified down to the assembly level.