It's his trademark style.
Not only is he a 'money' orientated Boxer, he will manipulate everything about a fight with a contender until it is 'his' fight that he is going to have.
Mundine would do the same and many other Boxers do it as well.
But Mayweather Jr is the best at it - not only getting more money over the opponent, but for preparation, rules, etc.
He did it against Pacquiao and the Pac-Man caved in.
It was reflected in their fight - how Mayweather Jr dictated the fight and Pacquiao chased him around like a puppy.
To fight someone like Mayweather Jr (or Mundine) - one must just 'do it for free' and thus negate the possibility of being 'bought' and one must climb in the ring and throw money at them as well. These are both a start to saying to Mayweather Jr (Mundine, etc) is that you are more than happy to 'pay' to beat them up, let alone for free.
Professional Boxing doesn't have 'money' makers ranked that high. Kostya is considered by Ring Magazine as the GREATEST EVER of his weight division - because of his 'Professionalism' upon his performance.
Yes - act like a Professional and you should and will defeat the likes of Mayweather Jr (if you are up to scratch as well - but 'pound for pound' you should
)