Fremont sits in a mild temperate band - no deep freezes, no monsoon season, nothing that snaps a spring overnight. That's actually part of the problem. In a harsher climate, wear announces itself fast and gets fixed. Here, a slightly off-balance door or a spring losing tension can run for years without anyone noticing, because nothing forces the issue.
The bigger driver is age. Housing across this service area was built mostly between 1955 and 2005, with the median landing around 1966, and the bulk of it going up through the 1960s and 70s. A torsion spring rated for around 10,000 cycles doesn't care what the weather's doing outside - it cares how many times the door has opened and closed since Nixon was in office. On original hardware that's never been serviced, you're looking at metal fatigue that's been building quietly for decades, mild weather or not.
The lack of extreme heat or cold also means owners here get less warning than they would elsewhere. No cracked panel from a hard freeze, no warped wood from monsoon humidity - just a slow loosening of bolts and a spring that's one cold morning away from letting go.