"The road to hell is paved with good intentions" Honest mistakes happen all the time. If the pilot honestly thought he had enough fuel to get you to London, but you found yourself swimming in mid Atlantic, would you not want his license revoked?
The rocket engineers of the Columbia disaster voiced their concerns about the infamous O-rings, but unfortunately had no authority to ensure that they were redesigned. Not sure if they had any responsibility or not to do so, but if they did, it didn't work out. What is pretty sure is that someone reviewing a design submittal for conformance, is rarely qualified to do any design. That's why inspectors are not PEs.
A contract engineer, "inspector", or a "plan reviewing engineer" if you will, is not required to be a PE, because he doesn't design anything. He ensures conformance to the specs and dwgs made by the EOR. Furthermore their experience in what they may be reviewing is not sufficient to do any design. Who gets to do dwg review even at engineering companies; the new guy. Or maybe the guy is a PE Electrical by training and experience, but there are prestressed concrete bridge girders on the dwg he's looking at today. It maybe just fine if all he is doing is checking conformance, but you want him to do what, recognize that there are not enough strands in some cable, do a redesign on a napkin and call the mayor?
In private industry you are correct, the internal engineer reviews plans of outside work and is responsible for its success, but when I do that, I do not redesign the contractor's work. I tell him I need an acceptable solution. Why? Because I usually don't have experience, and certainly not the time, to run enough CFDs, or the latest pipe stress programs to do so. These projects take 100Ks design hrs. Scott could beam me up to Enterprise when I finished. And there is another reason.
Outsourcing design is also a tool used by private industry and gov both to separate responsibility and avoid future liability when possible. If our facilities don't work, we want a very large and well insured engineering contractor, or constructor to sue for damages and make it right. They long ago found out that my bank account doesn't hold enough billions to make it worthwhile to give me any responsibility for that. I can't be monetarily responsible, so why make me legally responsible. Shareholders aren't interested in legal anyway. For which I am very glad. Maybe I'll get fired some day if things go badly, maybe not. I would love to know enough about subsea production facilities operatig 1000m underwater to be able to design them, or redesign them for the contractor if necessary, but about all I can do there is tell the contractor that the dwgs dont show the right orientation or the distance from the platform is short by 50m. Nobody is an expert on everything these days.
Do you want gov to hire an army of experts to do PE level design reviews and redesign of everything? I don't think that's practical. Or have the gov responsible for AND doing the design. Wasn't the last time they did that for the Manhatton Project, or was it the Panama Canal?