Those are both bad examples. If the joist system was compliant with 2x6, using 2x8 would be completely acceptable in the US. It's actually common to move up one size to reduce deflection. But you could also use 12x12 if you wanted to. There is no limit imposed on how far beyond code you go.
The stapling issue I don't understand at all. If it's building paper or something like that it has to stay up until the siding goes on, the inspector doesn't give a rats ass how you make it stay there.
Overall the code is sensible, there some odd items you'll come across that don't seem to matter, but overall it's primary purpose is to insure that minimum standards are met, and that the structure is sound and habitable.
My experience with inspectors over the last 35 years is that if they walk on the job and it looks like you know what you're doing, they aren't going to spend an hour trying to find something wrong. They can be very helpful when you run across an odd situation and don't really know how to proceed.
Here in California there are also some serious problems with not pulling permits. The first is that if there is a fire, and the insurance discovers the work was done without a permit, they won't cover the loss. Even if there is absolutely no doubt the unpermitted work wasn't the issue. The reasoning is that they don't insure illegal work, and any work done without a permit is by definition illegal, no matter how well it was done. There can also be problems at the time of sale. Unpermitted work can actually decrease the value of a home, and every buyer uses that bargaining chip to full advantage.