I think this is the answer. At investment banks (I interned at one once) the tech people were a cost center, not a profit one, and the power structure reflected

I think this is the answer. At investment banks (I interned at one once) the tech people were a cost center, not a profit one, and the power structure reflected that, whereas with many Silicon Valley type companies, it's the opposite. I guess this is what people refer to as having an "engineering-driven" culture.