Ah gotcha, the problem isn't that it's a vague job title, the problem is that the job description for a particular position may not set expectations clearly enough
No - I'm trying to say that people often don't even know what the DE really needs to do. They know they have back-end problems, and need someone to clean them up.
But often the hiring manager believes it's probably mostly SQL or mostly python, and advertises that. They really don't know - because someone left, and they are trying to replace them.
So you get there, and talk to the hiring manager, and they're like "are you good in SQL?".
Then you talk to someone closer to the problem, and they're like "most of it's in Java - how's your Java?".
Then someone even closer to the position says, "well, most of the work we need done is really in Scala".
It's your job to just take it over, and make it happen. "Fix the data" - using our existing patchwork of tools ...
This isn't always the case - but given the nature of the problem, this happens a hell of a lot more often than with Soft Eng's.