A lot of White Center's houses went up around 1975, a decade or so before the wider service area's median build year of 1983. That matters here because a door installed with the house is a first- or second-generation steel sectional - single-layer steel, no foam core, often in one of the flat embossed finishes that were standard through the '70s and '80s. Those panels don't flex the way modern insulated steel does. A stray basketball, a backed-into corner, a rock kicked up by a mower - any of it can crease the steel permanently instead of just scuffing paint.
The area sits in a cold, moderate climate band, which means these older single-layer panels take on condensation on the inside face through the wet months. Over enough winters that turns into rust starting at the seams and bottom panel, right where water sits longest. Once rust has eaten through the galvanized coating, patching doesn't hold - you're replacing the panel, and matching a 1970s profile and color isn't always a straight order from the manufacturer.