You might be underestimating how many high-value assets we are surrounded by that are well maintained and extremely reliable. They tend to blend into the background because there are so many.
Obviously mistakes happen, but the central point here shouldn't be controversial: a rational and greedy agent maintains their assets. Otherwise they sorta get booted out of of the club of people who own assets, because their competition would have similar realised returns and a fully functional asset (if maintenance is possible it is usually a more economic option than building from scratch). If the government is going to obsolete your asset by force, then the agent's decisions will change, but the agent isn't exactly in control of their situation if the government is stepping in.
Capitalists, funny to say, are actually highly protective of their capital. If you have an asset worth billions of dollars no rational manager would take a risk on it; the maintenance generally gets done. Billion dollar assets generally don't get associated with reckless people.
That sort of short-termism no-maintenance approach is more likely a symptom of the political risk of running a reactor. Maybe they want to invest in an upgrade, but there is a reasonable chance that politicians will shut you down (eg, as happened in Germany). In that sort of environment, because the asset is at risk, the rational course of action switches from maintenance to exploitation.
And I'd bet the plan managers would live locally, you'd be silly not to. They don't expect their plant to melt down, or they wouldn't be willing to be the plant manager. Nobody would be involved if they didn't expect the plant to function, they'd shut it down.