"over-engineering" something can't make it last forever, can't prevent it from eventually wearing out. If that's the plan, it just postpones the day when people suffer. As you say, these things were engineered for the long haul but the people harmed in Santa Rosa fire that the collapse of a pylon caused probably aren't impressed by shear lifetime.
Father: Son, some day, all of this will be yours. And since we don't expect to do maintenance, some other day, it will explode and kill you or your grandchildren.
If you build something to last 100 years, you leave little incentives for maintenance and all but guarantee a catastrophic failure a century from now.
If you build something to last 10 weeks, you're creating a lot of waste - wasted labor, money, energy and natural resources, involved in producing and shipping replacement parts, as well as performing the maintenance job. You're also making everything that depends on your construction more fragile - the system is always a couple weeks from catastrophic failure, so it won't survive a localized crisis - like a natural disaster, pandemic, economic problems, maintenance company going bankrupt, etc.
So what's the correct trade-off function[0] here? How can we minimize waste and maximize reliability, while ensuring necessary maintenance happens on time?
If you build something to last 100 years, you leave little incentives for maintenance and all but guarantee a catastrophic failure a century from now.
-- My comment about a family above was sarcasm, not a picture of reality. A large organization is quite capable of determining what maintenance is needed for its infrastructure and doing that maintenance. PG&E knew quite a while back that they were in trouble here. It wasn't the long time frame but profit and regulatory incentive structure that drove their decisions. They'd have done the same for short-lived infrastructure. They've done the same thing in the case of tree-trimming; something they should be doing constantly and haven't (note, living in Portland, or, the local utility, Portland General Electric (called PGE for kicks), trimmed trees with abandon, which is better than the alternative).
Sure, designing for maintainability is a nice strategy but fixed lifetime + replace is an effective strategy too.
Basically, the whole line of reasoning about short versus long lifetimes is a complete red herring and the neglect and decay of PG&E's infrastructure was an explicit on the company's part and documented as such and has nothing to do with how infrastructure was designed.
> If we were to eliminate waste, less people would have jobs.
... or more people would be available to take on work that's more needed and not currently being done. Otherwise, why have machines and technology, if they all primarily automate tasks your fellow laborers could be doing?
I think that work which exist only to provide jobs is a waste at societal level. But it's also a waste at company level - why would you make your product labor-intensive to maintain, where you could make it robust instead? In reality, the trick is to ensure you're not the one paying for maintenance - and then you save money by making more fragile products.
Fail safely. In this case the failure of the beam should have broken the cables or fallen in such a way to not create a pathway across the non-zero phases.
Father: Son, some day, all of this will be yours. And since we don't expect to do maintenance, some other day, it will explode and kill you or your grandchildren.