That's why understanding the domain logic requires cooperation between programmers and those who understand the domain.
It might not be that they don't understand the domain "deeply enough." Maybe they understand it in the way that is relevant for their work, which typically doesn't require formalization.
Making sure this collaboration actually happens is one of the big topics of Domain-Driven Design. We can't just expect to be given a correct model; teasing that out is part of our job. If the spec is nonsense, we should say that and try to fix the process.
It might not be that they don't understand the domain "deeply enough." Maybe they understand it in the way that is relevant for their work, which typically doesn't require formalization.
Making sure this collaboration actually happens is one of the big topics of Domain-Driven Design. We can't just expect to be given a correct model; teasing that out is part of our job. If the spec is nonsense, we should say that and try to fix the process.