They are marine hunters and Mihawk's superior Buggy still doesn't have equal bounty to Shanks.
Captain hard caps subordinate bounty
Zoro is more or less stronger than Luffy yet his bounty is 1/3rd
Even when he had equal fight with Luffy his bounty was less
Meaning if subordinate is seen as equal of captain his bounty is 1/3rd
So for Mihawk to have higher bounty than Yonko doesn't that mean world government perceives him as 3 times as strong as yonko??
Mihawk casually rejecting Yonko title is also evident of just that btw.
Like Yonko title is such a joke to Mihawk..it will take him one micro second to get it.
Where as Shanks trained his whole life
Learned swordsmanship of your daddy
And is still far below WSS level