The housing stock through this stretch of the service area, Shady Shores included, mostly dates to the 2000s, and the climate here falls in the moderate-heat band rather than anything extreme. That combination matters more than people expect: it's not that the heat destroys cable fast, it's that twenty-plus years of ordinary thermal cycling on hardware that was mid-grade when it was installed is enough to fray a cable at the drum where it bends hundreds of times a day. Houses from this era also commonly used lighter-gauge cable than what gets installed today, so the margin before failure is thinner to begin with.
We don't see the older galvanized-cable failures you'd get on a much older house, because this part of the area simply wasn't built yet. What we do see is cable failing at the same point on a lot of doors from the same few build years, which is less a mystery than a pattern.