In software you do this every time you change jobs, and the randomness of the process ends up dictating which company you work at.
As an attorney, when you change jobs you've already passed the bar.
I really don't know but isnt the bar generally the same types of questions every year? Like the SAT? It feels like preping for interviews is hard in part because you could be asked anything from reverse a doubly linked list to design facebook. If it was a smaller set of questions it would be a lot easier to study for.
There will always be some sort of arbitrary selection screen as long as there are more people who want these high paying jobs than there are actual high paying jobs.