No, this is not 'normal prudence', it is completely off-the-wall conspiracy stuff. If you think this is normal then that is really problematic.
What you call conspiracy is normally named classic strategy by all who study and use it. So any normally prudent State do it's best to avoid creating potential threats potentially used against itself. Some do not just because those threats are corruption-fueled economy. And again we see countless examples in just the very recent history.
The cases you list are the exceptions, not the rule. Fact: undersea optical cables would be trivial to destroy. But as a rule they work well. Fact: water infrastructure, gas infrastructure and power infrastructure is vulnerable. But it actually works quite well. Fact: logistics infrastructure is fragile, as are most buildings. And yet, most of it seems to hold up quite well. Ok we get the occasional crazy person but that doesn't mean society grinds to a halt or that we are going to re-do all of our bridges, crossings and foundations.
Hardened? No. Design to minimize unpleasant events? Yes. Just for instance did you lock your hose door? It's pointless since thief can still going in and locked or not the chance of being stolen it's not that much. Even that we still produce doors with keys to lock them, try finding a front door without in the market to discover it yourself.
> The cases you list are the exceptions, not the rule. Fact: undersea optical cables would be trivial to destroy. But as a rule they work well.
Sure because they are useful for all parties.
> Fact: water infrastructure, gas infrastructure and power infrastructure is vulnerable. But it actually works quite well.
And have seen a significant spikes in attacks... However again: just see Russian gas to the EU: both parties, with Ukraine as third can destroy the ducts, they do not do that simply because they are equally interested in them: Russia need to sell gas, they have already made the infra, they want money. EU need the gas, without it too many industries will stop. Ukraine use that gas itself and even if they decide to take the damage BOTH EU and Russia will be against them for the collateral damage they suffer.
Actually electricity from Morocco to UK, if cut touch nearly only the UK, so it's a potential target.
> Fact: logistics infrastructure is fragile, as are most buildings. And yet, most of it seems to hold up quite well.
Oh yeah, sure, so the big supply disruption so far is just a small issue in your opinion? In buildings term the fact that our cities can't evolve anymore and we need them evolved is not an issue, to a point we have made the ONU New Urban Agenda? Not counting the continuous debate of low quality buildings, in general, but more in particular big ones where issues might led to far bigger consequences...
> Ok we get the occasional crazy person but that doesn't mean society grinds to a halt or that we are going to re-do all of our bridges, crossings and foundations.
Sorry for keeping such rude tone up but we are actually re-do the society, it's a never-ending process and we are here in a bad shape also thanks to those who say "anything is well, we can continue toward infinitum".