That should be obvious. Most people I've worked for can be challenged in private if you've actually got a point - even if you're shot down in the end. The ones who are still assholes when handled correctly are usually not worth working for. The best ones can handle a public challenge on the merits of course.
That's exactly what different cultures look like: it's absolutely not obvious in Eastern Europe where I live. We call each other out on our BS freely and directly, and almost nobody ever gets offended.
It is quite the cultural shock for many of us when we suddenly have to sugar-coat and positive-tone-first every work criticism we express. It can feel like a huge waste of time and energy while if somebody tells me "Dimi, your code in module X sucks!" and I'll just laugh and say "dude, I had only a day to finish that, sorry -- if you don't like it, talk to the boss to give me one more week on it and it's going to be swell".
So no, such things as the one you quoted aren't obvious at all for many. I'd even argue they are only prevalent in the USA but I've seen evidence in both directions so I can't claim anything absolute there.
I sometime am, and will continue to be that guy.
At least partly because it's the right way to handle post mortems, but partly because coworker X is only a symptom of the problem - and the underlying problem here is a manager who hasn't got a process in place to ensure Friday afternoon rush fixes on production don't happen. That's a process problem which is neither your nor coworker X's fault. That's my fault. Sorry...
(And maybe coworker X is a serial offender for this type of fuckup. Also my fault.)
I wouldn't rush to blame you if you were my manager. It's not the manager's job to breathe down everyone's neck -- they have to make sure to foster the right culture (like don't push potentially breaking changes to production at Friday afternoon) and ensure that the people hired are actually able and motivated.
From then on though, all bets should be off. Maybe the guy/girl had an awful day and is otherwise excellent. Maybe they felt pressured due to miscommunication (or a coworker being an ass and they took it personally and figured they'll speed through the task), or maybe they simply were novice in that particular problem or technology.
None of that would be your fault.
"He/she knows they screwed up. No need to pour salt on the wound."
Which is completely fair. But I've also seen fairly clueless people in responsible positions screwing up again and again and again and never being called out -- and those scenarios are not okay.
One kind of employer only retains crappy employees.
The other gets all the good ones.
Health care industry coding seems to along the lines. Solve the immediate issue. A few years later the complexity is off the chart.
You ain't seen nothin' then.
Try challenging an elder boss in Japan (or China or South Korea, but Japan is especially bad) and watch what happens, for example.
I find that very few cultures allow challenging authority like the US does.
Then you have limited experience with Japanese bosses.
Under most circumstances, they simply avoid trying to commit to ANYTHING. They will never give you a definite yes or no and will move glacially slowly.
However, when driven to against a wall in which they must make a decision, it is fairly common that they can, and will, spew some of the most jaw-droppingly stupid things, and nobody will ever contradict them--certainly not publicly.
Yes, when things go really bad, they will have to apologize and fall on their sword. However, the failure has to reach epic proportions before that will happen--normally they just shovel the blame onto subordinates exactly like US bosses.
If you are using this as a metaphor for a decision you personally consider stupid, then maybe.
If it's actually putting diesel in a gas car, then no, I can't imagine any case in which an intern couldn't safely tell that to their director or CEO.
When something is obviously not going to work akin to diesel in a gas car, I have never met someone who wasn't willing to at least take a second look at their "solution".
Most people are very hesitant about giving honest feedback even in US businesses because of these pressuring forces. If your manager wants to put diesel in a gasoline car, you often have to agree, then have a sidebar conversation directly with that person so their negligence, ignorant mistake, or intentional malice isn't put on a large group or public display.
Very few US workers are in positions to give blunt feedback. This was pretty common in software development due to leverage developers had but it's, IMHO, been on decline.