Non-software engineering doesn't excessively use formal methods. Only where required. (Like where a system is tightly optimized.)
For instance, in electronic engineering, you don't use the most accurate model of a diode at all times. Sometimes it's just a one-way valve. Sometimes, it's just one-way valve with a 0.7V drop (if silicon).
In mass production, you will not get the accurate parts needed for the most formal model to be justifiable, and the cost of those parts would not be justified in most of the circuitry.
For instance, in electronic engineering, you don't use the most accurate model of a diode at all times. Sometimes it's just a one-way valve. Sometimes, it's just one-way valve with a 0.7V drop (if silicon).
In mass production, you will not get the accurate parts needed for the most formal model to be justifiable, and the cost of those parts would not be justified in most of the circuitry.