Bounty Hunter? Did we seen good Bounty hunters yet? Can Johnny catch a guy like Crocodile? Of course not
Who can catch the pirates? Citizens? Can they cath devil fruit users, logia? No.
Then, Pirates? They can, but, what do they do once they are in MarineFord to get the Cash? They are pirates, they are catched and send in jail. Exept for ppl like BlackBeard who wants to be Shibukai.
Then, it seems that only the Marine can do something vs pirates.
Speaking of Kuro, he does not want to be a pirate because he always has the Marines behind his ass. But, the marine does not care of the bounty right? It's their job to do it.
So, what is the point with Bounties if nobody can gain it?
Until we see a strong Bounty hunter group, this system will be illogical.
Let's explain it: The Marine wants to eradicate the pirate era. For what we have seen, the pirates are proud of their bounties. It start with Chapter 1 with Higuma. We have tons of examples in Jaya, Straw hats pirates well mostly of the pirates are proud of it.
For the pirates, bounties determines the strengh " I am better than you because my bounty is higher". In this case, it create a competition, the pirate who get a high bounty feel stronger that the pirate who does not have one. They want increase it.
Also, bounties determines who are the best pirates. The High bounties are the best pirates. So, it create famous pirate. " Wow , look at his bounty it's Luffy!"
Without bounties there is no fame, pirates are unknow. The Marine wants to eradicate the pirates, but they create this era, in creating legends who have astronomical bounty.
Since no one apparently can catch the high bounties, there is no point to put it. But it's a shonen, and bounties are cool. Thats my point.