Well, they may actually "sign off" in particular jurisdictions, but not in every jurisdiction. Even when they do, it's not a "given".

No matter the jurisdiction requirements, it is of the utmost importance in contract law that one remembers this when it comes down to brass tacks in "signing off"... (I, me, gnu, am the one who penned this)... "Just because I made an error in not noticing your error during my general arrangement, cursory, and visual inspection does not relieve you of your responsibility for your error in your performance of your work under your contract and under law and under code." That usually brings THEIR lawyer back to the table VERY quickly and with tail between legs.

To say that a bunch of government inspectors are gonna save yer ass in each specific case is just not reality. The Bob Vilas and Mike Holmes of the world make a shitload of money doing TV shows, but, that is what they are... TV.

As for "arguing", I hope youse never have to do so in court. If you ever do, I am available. But I charge a shitload more than any government inspectors. And, I require payment up front and I charge a half day just to sign the contract.