Indeed, and in addition to selection bias towards better programmers, there is another selection bias implicit in this. A shop that makes the decision to write

Indeed, and in addition to selection bias towards better programmers, there is another selection bias implicit in this. A shop that makes the decision to write their stack in Haskell do it with an intention to focus on correctness. I reckon that such companies would consequently invest in other practices like more tests, higher code coverage and more intensive code reviews resulting in code with fewer errors. This is in stark contrast to a startup that may have hacked together a POC in Python, and once it worked, with a little bit more spit and polish put it into production.