All softwares are not created equal. Some are born as the law and some as graffiti on the wall. A lot of code these days is just disposable.Its only used for few months and thrown away for something new. The internet and mobile apps always stays in a fluid state as user requirements, devices and the environment keep changing. It would be unimaginably hard to provide mathematical rigor to every html page-scrapping script I write. Sure there must be mathematical rigor in software that has some serious uses like in real-time systems, rockets, cars etc. I would be very upset if my car vendor does not apply some serious math to their code for car's critical systems and I think they do. and as far as my mobile app is concerned I am happy with the Xcode's static analyzer.