I thought about this, too, but I see alot of these jobs with Python requirements being a one-way street, so to speak. A physicist or aerospace engineer might have more chances to work with Python in their jobs, but a good Python developer would have a hard time trying to get a job where the primary skillset requires a degree in Aerospace Engineering.

In general, most of the jobs in Python are side-effects of the field they're used in and not based on being a good Python developer.

I'm sure there are exceptions, but in my localized job searches, Python isn't seen as the primary skillset, merely a 'nice to have' one.

This is the real difference between Ruby and Python, in my experience too. You're more likely to find Ruby used by people who self-identify as programmers and more likely to find Python used by people who self-identify as some other job - but the amount of code each group writes is probably about the same.

I've seen a lot of postings like this but I've also seen several lately where Python is the primary requirement. For example, I've seen several openings recently for people in the financial industry with no hard requirements beyond Python experience.