You've missed the point. If one has to pass examinations then the examinations can be used in a discriminatory or unreasonably restrictive manner--in parts of the US they were used to prevent minorities from voting--the tests were designed in such a manner that the scoring was a judgment call, and in the judgment of the scorers no black person was literate no matter what answere he gave while any white person was literate even if he couldn't read. In parts of the US there have been requirements for such examinations to be taken in order to be allowed to own a firearm. The tests were given very rarely in unexpected places with no prior announcement and the number of applicants allowed at any given session was very small--in effect the only people who were allowed to own firearms were those who had enough political influence to be informed by word of mouth.
Accidental shootings in the US are quite rare. More people die in bicycle accidents than in firearms accidents, but we place no restriction on the ownership of bicycles (and we should--an amazing number of bicyclists don't seem to be aware that they are expected to obey traffic laws).
Oh, how is it "easily circumvented"? The only manners I am aware of by which it has been "circumvented" are straw man sales, which are felonious crimes, and private party transactions which are not regulated mainly because Congress knows damn well that trying to regulate them has about as much likelihood of success as an attempt to herd cats.
A requirement for a license would not prevent either class of sale.
Further, according to the US Constitution and to the US Supreme Court, the ownership of firearms is a right, it is not a privilege, and so is no more subject to licensing than is free speech.
Many states in the US have "must issue" carry permit laws that state that anyone who applies for a carry permit must be issued one unless he is a convicted felon or otherwise prohibited from owning a firearm. Can you give us an example of _one_ incident in which as a result "10 other people pulled out handguns and started shooting at each other"?