I actually think it's OK to ignore the problem domain in job ads for almost all programmers. When I was working on systems to support the manufacture of medical devices, and later on systems for support nurses and patients with managing drug use and stuff, I didn't have to know much (or, indeed, anything beyond what any well-educated layman would know) about the problem domain. I was just writing code to gather and process data, and I don't care whether your data is incidents of adverse reactions to a drug or the migration routes of the Greater European Spotted Bat. All I need is to be familiar with the tools that the employer uses, to be intelligent enough to learn the terminology and the basics of the problem domain, and to be confident enough to ask a medic or a bat expert questions when I don't understand the problem, or I think their specifications are vague etc.