This area's housing stock is mostly 1960s and 70s construction across the named communities we work in, and a lot of those garages still have their original or first-replacement doors. Those doors used steel gauges, panel coatings, and wood-composite inserts that were standard decades ago but aren't what's on the shelf now. One dented or cracked panel on a door like that isn't a simple parts swap - it's a search for a profile nobody's made in years.
The mild temperate climate here plays a role too, just not the one people expect. There's no freeze-thaw cycle splitting panels apart the way it does in colder regions. What you get instead is sun. Years of direct UV exposure fade paint unevenly and warp thinner steel or composite panels, especially on south- and west-facing garages. The damage builds slowly - a panel that's slightly bowed or a color that's drifted from the rest of the door - until a single hard knock (a trailer hitch, a bike, a basketball) turns a cosmetic issue into a structural one and you're looking at replacement instead of a touch-up.