North Palm Beach's housing is older than the typical stock across the rest of the service area - a 1972 median build year against an area-wide median of 1981, with most of the surrounding 16 named areas built up more heavily through the 1980s and 90s. That decade-plus head start matters for panels specifically: doors from the early 1970s were often narrower-sectioned and used coating and steel gauges that have since been phased out, so they're reaching the end of their service life while a lot of their neighbors are still running newer stock.
The mild climate here doesn't accelerate failure the way harsh winters would, but it doesn't stop it either - UV and humidity wear a panel down slowly over fifty years instead of cracking it in five. Combine an older build year with that kind of slow, steady wear and you get exactly what we see on these calls: one or two panels that have simply outlasted their finish, on a door that's otherwise sound enough not to need full replacement.