Tell me you don't know the first thing about engineering without telling me...
This is the engineering process. If you put five engineers of any discipline in a room, you will get five different answers. Every contractor and architect has their own ideas about how things should be done.
Furthermore, we do build houses this way, even in the modern age with building codes. The builder is going to do whatever they can get away with and this is a universal truth. The only reason bridges are held to such high standards is because of the monetary cost of a collapse.
The "norms" are not what you think they are. They're tradition, they're "we've always done it this way". What you're talking about are laws written for public safety. Those laws only exist because we tried and failed to do things a certain way and the cost in money or lives was untenable.
> "I recognize a good solution when I see it" is just not good enough for a serious engineering discipline.
You're conflating engineering with science. A scientist will rigorously test and validate, but a huge part of engineering is just recognizing a good solution. Of course there's a lot of testing and validation in engineering as well, but not with the kind of rigor you're implying.