There's this place for formal proving that most people won't get to and think it's stupid. I was such person some time ago, but then started to work on the system that: Required 2-3 months for implementation, had no room for error, made processing mistakes cost in thousands of Euros (even silly things). Than you start to wonder "hmmm... how can I use something better than just good practices and judgement? How can I _prove_ design A works".

And usually there are tangible problems to avoid: Ensuring that money won't get lost in transaction. Making sure that legal paperwork will be delivered or returned on time. Or that CSV file costing arm and leg for a single row won't have more rows than necessary. Many of these problems are borderline paradoxical. It's known that (as with Two Generals) there are no complete solutions. Usually it's like playing a catch with reality. A game that goes "what happens if we duplicate money mid-flight?" - "which system is source of truth in case of fraud", "do we rather risk false negative or accept MIA state" etc.

Sure, it's fun to model a crossroad with streetlights and a chicken just for kicks, but the main "why?" for formal proving is having "this design is good because I've seen the proof of it" moment.

But what kind of questions are asked is just as important. I can bet asbestos met all the standards it was checked against :)