There's a big difference between a developer going off and writing something in one of the top five most used languages in the world and doing so in Scala.
Python may seem simple once you know it, but going in blind there's plenty of traps to bite you. Significant whitespace for one.
1. picking a language/tool that a company doesn't have personnel with experience using it
2. picking a language/tool that is esoteric, which generally implies #1 as well.
#1 on its own isn't great, but generally when sticking in the java/python/ruby/javascript/php/etc...mainstream languages, there's a lot more documentation, and there's a higher chance that _someone_ in the company will have some familiarity. If nothing else, it'd be easier to hire a replacement for.
If it's just one component, implemented by a single dev, it really can make more sense to understand what it does and rewrite it in a language that's common in the company.
It's not only the language but the framework. For example I know javascript well enough but I now am quite a noob with Ember in my new role. I would say the framework is just as important as the language, at least when doing web development.