Not all architects know. Source -- Am in month 21 of a construction project. Have caught more than a dozen mistakes made by both the architect and the GC's subcontractors.
But that's normal, there are varying degrees of competence in each trade. If someone asks who should they hire to develop a software solution, the answer is "a software company", even if there are software companies that develop awful software full of bugs.
Slightly sarcastic a bit, but isn't the point of all that engineering schooling, certification, titles, social prestige etc some kind of assurance that those people don't make mistakes? Or if they do, very slight ones? In a sense you cannot have it both ways right?
The idea behind is surely that, but it doesn't mean they can screw things anyway... the difference is that they will be accountable by law for it (which is an important difference, especially if compared to the world of THIS SOFTWARE IS PROVIDED "AS IS")
I guess in theory that would be true, but in practice (at least where I live), there is no accountability. So yes, doctors, lawyers, architects/engineers etc, get all the prestige and social status, without the downsides.
There was an exception though, like 10 years ago where the doctor was removing a patient's appendix and damaged major artheries. The poor patient lost the leg and the other one is not functioning well. They've sued privately (and had top lawyers) and after a very long process they've kind of won some meagre settlement. What was actually interesting was the fact that the major regional hospital never had a "doctor's error" in the last 20 years, only so called "complications" (which was "nobody's fault").
Doctors (and similar) don't get insurance against damages at all. Why would they?