Engineering is the discipline of designing and implementing solutions that achieve desired outcomes, using limited resources, while satisfying a defined set of constraints and minimum acceptable standards.
We have way more resources now to achieve way higher standards.
I don't think so. The article refers to formal verification, but also notes that proof checking should be done by humans. We don't have enough capable humans for that.
As a general rule, building things as an engineering project (according to engineering, whatever you want to call it) doesn't prove they work. Rather, it proves they don't fail in specific known/defined ways. There's always ways they can fail that aren't known/checked, and frequently ways that aren't considered important.
Kind of like automated tests in software development. Except the people that pay for the engineering stuff are more likely to pay for the extra tests, because of liability.