Competence is tangential. They're happy to allow the idiots, so long as they aren't so stupid it makes the organization or the government look bad.
The way licensing fundamentally works is industry basically strikes a bargain with government to it's benefit. Government lets the licensing organization run a supply cartel and collect protection money (dues, test fees, whatever) so long as they promise to enforce (low) minimum standards along the way. Government gives licensees favorable treatment in court (statutory limits to liability, licensed professionals opinions are more equal than average peasants, etc, etc), etc. And all this stands so long as they do whatever the government's rules say (to the detriment of the customers). And of course the professionals make money hand over fist (or at least more than they're worth) in the process because the licensing organization constrains supply.
Society gets just enough scraps to provide the political will to get it done and keep it rolling (the low minimum standards).