That was the first thing I noticed as well. I don’t blame him mind you since I would have assumed they are better and easier as well but recently my brother who is a carpenter told me you have to use nails they are needed. This just reminds me that being handy is good but knowing code is critical for some thing. In this case he will probably get away with just screws.
Have an architect as a friend? I have such a friend, and it's always fascinating when talking to him about building codes and such (such as the type of covering for network cables in a commercial setting depends upon the type of A/C used in the building, due to concerns over fire hazards and air intake).
You can always do it the hard way and have an inspector tell you what is wrong, fix it, repeat. The whole point of inspection is to get it right. This method isn’t cost efficient for starting. Find friends to ask questions before starting to reduce inspection failures.
The simple answer is testing. When you go to school you get a test that certifies you have a basic knowledge. It may not cover every aspect but will teach you where to find the answers you don’t know.
A while back I looked briefly into what it would take to be an electrician, and it seemed like there was quite a lot to know. I wonder how soon you get to the stage where you could wire up a shed like this with full confidence that you've done everything to code.
From there, how many other subjects do you have to get right? I learned how to swing a hammer as a kid but I wouldn't know jack about designing load bearing structures, weather proofing, foundations, hanging windows and doors, etc — let alone plumbing, HVAC, etc.
Electrical is a whole field of expertise. To wire a shed to code however is not that hard. I’ve done my dad’s tiny home personally and then had my electrician friend come in after and said it was all done and to code. Some of the skills overlap but usually the carpenters do the work and at a certain point the electrician comes in and does all his work then the carpenter finish up. The real secret to getting fully comfortable is doing an apprenticeship where someone is going over all your work.
In my area, community colleges have trades programs for such things. I've gotten overrides for pre-reqs when I've audited classes for hobby rather than for the certificate/degree, allowing me to take the few core courses that cover most of what I'll get into in my projects.
Also, when applying for a home-owner permit, my city requires you pass a short test showing you know the basics of the code (not nearly as in-depth as certification exams).
