This.
Moreover, an exam for a course is, to some extent, an assessment on how the course was delivered. And an interview for a job has a much larger scope.
Oral exams have an entire other bunch of issues.
Just looking at the professor side, beside time, I imagine it would be very difficult for to grade with same meter an arrogant student, a dismissive one, a smelly one, an eloquent one, or even the first and the last one in the same session.
Totally agree.
I might a bit partial to that, because I tend to underperform multiple choice tests for overthinking, but I've really the impression that open ended questions test knoledge much better and make it more difficult to cheat.
Beside that, having almost nothing to do with cheating, another good thing in the French system is the continuous grading: labs were graded, projects were graded, small intermediate tests were graded, so you really do not study for just the exam (actually often you do not study at all for the exam).
(beware: my experience is limited to a single grande école I attended).