I build the boring parts well.
Data sync that never loses a record. Pipelines that recover without waking anyone up. UIs where you forget there is a server behind them.
I also care about the parts users actually touch. How a workflow feels at 100 nodes, what happens when someone clicks before the data arrives, where the loading spinner should never appear in the first place.
Most of my work is closed-source, but the problems are the same everywhere: make it correct, then make it fast, then leave it alone.