There's a particular kind of silence that happens on a call when a regulator asks, "Can you walk me through exactly how this number was calculated?" and the person on the other end has to say, "Let me get back to you." I've been on that call. It is not a fun place to be, and it usually isn't because anyone did anything wrong. It's because the pipeline that produced the number was never built to answer that question in the first place.Regulatory reporting, whether it's a liquidity return, a capital calculation, or something more niche, has a strange property compared to most data engineering work. Nobody outside the team really cares how the dashboard behind it looks. What they care about is whether you can prove, months or years later, exactly where every figure came from, who touched it, and why it changed between two reporting periods. That's a fundamentally different design goal than "make the report run fast," and honestly, a lot of pipelines get built for speed and convenience first, with auditability bolted on afterward as an afterthought. It shows.