Scala has a steep learning curve, so we're looking for devs having at least one or two real production projects (that aren't using spark) on their belt. It turns out to be quite a challenge to find someone who have experience in the ecosystem and the language, AND who _like_ working with it.
Plenty of developers have significant Scala experience and like working with it, but the demand greatly outstrips the supply - if you look at a chart of average salary by language Scala is a huge outlier.
