I agree with chetanahuja that there are more "single developer's technical problems" in established software companies rather than startups. During my time at

I agree with chetanahuja that there are more "single developer's technical problems" in established software companies rather than startups. During my time at Google, there was an engineer next to me working full-time on GCC, because found compilers most fun and technically challenging. On the open-source version, not a private branch or anything. Very few startups would have the scale and stability to allow an employee to work on something that maybe delivers 5% faster code or 5% faster build times in a few year's time.