Applications for the police are open to the public. [] At no point in the application process does it say that they will only recruit from people who's.... "thing" in life is to put a uniform on and bully the rest of us with the powers they are given.....
I really think you need to understand the concept of "self selecting".
Let's try another way.
People choose to be police officers. They aren't dragooned into it. No one makes them.
So the pool of recruits is already limited to people who want to be police officers.
And some of them will want to be police officers for all the wrong reasons. Who will not be easily spotted by the existing police officers who wanted to be police officers for all the wrong reasons.
So stop trying to blame "the public" for the fact that the police force as a whole is unable and possibly unwilling to weed out people who really, really, really, really should not be allowed in.
If this discussion wasn't taking place in the wake of any number of people murdered, raped, assaulted, harrasessed, or falsely accused by the police such distinctions would be less critical.