Hey @jmcgirk - thanks for the welcome!
There are quite a few areas/industries where other models are used for mission-critical systems. Rail is one (e.g. https://web-archive.southampton.ac.uk/deploy-eprints.ecs.soton.ac.uk/8/1/fm_sc_rs_v2.pdf) (quite an impressive track record for bugs in the abstract!).
The label ‘N-version’ programming can also be used here, with applications also extending to electronic voting.