Someone who knows what they are doing could probably write rice cooking logic that works pretty well in a couple days, and a beginner (like me) could almost certainly get something working in a couple weeks. There'd always be room for refinement after that, but I can't see that the code would be a limiting factor.

But likely you've hit on the real reason there isn't much competition on the low end: making an inexpensive fuzzy logic rice cooker is easy, but if it started selling well you'd probably be sued out of business for patent infringement. I now feel silly for overlooking this obvious explanation.