It's because most stuff that engineers and DS work on is to make money for a company. Most of the stuff is internal tools, something used by internal staff, etc. And when you "finish" the job it's not something physical and hard that you can say "wow look at that, look at what we built".

So basically you're working on a team without much autonomy (there's only so many ways to fit in your contribution or your model), there's very little connection to the end product even though you worked hard, and most of the time you're working alone just coding something out.

So: 1. Little autonomy 2. No grand physical end product 3. Little deep social interaction