Well, that's not true at all. Scientists care about performance, but it turns out that Python is really good for number crunching since it is really good for using very fast C libraries. I know people who use pandas to manipulate huge datasets from radar astronomy. Also, of course, it's used in machine learning. If Python was "only" used in situations where you don't care about performance, it would not be used in so many scenarios that definitely need high performance. Sure, it is not pure Python, but it's still Python being used, just used to orchestrate C libraries