What are the challenges in getting developers to build your startup's product?

Being a technical cofounder for my own startup and helping other startups in developer role, I can try to answers your query, from a different perspective.

Trust, transparency and communication are the biggest hurdles in early stage.

Non-technical founders are initally sceptical about revealing everything, until they have travelled a while with the developer. It makes sense, because the risk is more on his side than the developer.

Some developers can own the MVP and deliver the best.But some can vanish in the middle of development due to technical challenges or greener pastures.

Unless both developer and Founders spend time, iron out trust issues and build rapport, the collaboration will not be smoother.

I am a "technical person", so perhaps not as well qualified to answer your question from that perspective. However, I will try. The biggest problem I experience is that communication between "what I want" and "what I get" seems to fail a lot. Non-technical people collaborating with technical people have an inherent disconnect. Terminology is part of it, but I think the bigger problem is the difference in perception between what non-technical people imagine technology to be able to provide and what technical people believe are the limits of technology. The second biggest problem I experience is expectations matching. Some things are technically trivial that might seem almost impossible, while some things that are almost impossible technically may seem trivial. The solution to these problem has long been better communications, which takes someone who understands both sides (perhaps you) and can act as an intermediary while the two sides learn more about each other and how to interact successfully.

Fred, you brought up the main points straight away!

Indeed, communication is probably the key here.

Then, what would you say, whose job is it exactly?

In my mind, it is the CTO's job (but I'm strongly biased here hahah). A multidisciplinary guy in that position can literally save the company from early-stage failures.