I haven't seen the behavior that Serena got fined for, but John McEnroe was another 'ungentlemanly' tennis player. I wonder if her behavior was worse than his, or if he ever got fined?
Oh, yeah, Johnny Mac got fined back in the day, LOL. If memory serves, he even had to forfeit a match once due to his behavior. Honestly I think what Serena did was worse -- she threatened physical violence against a linesperson. No defense for that.