This sounds like the typical "its good enough" argument. Say we test the breaks manually nine times of of ten. This means we get really hard to diagnose bugs because "this did work when i tested locally". And users get more runtime errors because of half-assed development.

Type systems should be treated like maths, its either correct, or not. In the end, a typesystem is basically just that, its math behind the scenes, more specifically a genre of maths called category theory.