Roger Federer was fined just $1,500 for a berating an umpire with an expletive during the 2009 U.S. Open, and Adams pointed out that the amount of fines is at the discretion of the administrator of the four Grand Slam events, not the USTA.
The Women's Tennis Association (WTA) and United States Tennis Association (USTA) have backed those claims following Williams' straight sets defeat to Osaka.
Moreover, a source identified as a tennis "senior figure" told The Guardian, "There is a lot of unhappiness in the umpiring community because no one is standing up for officials. Will the rules change in Serena's matches?".
Women's governing body the WTA supported Williams and chief executive Steve Simon said the umpire showed her a different level of tolerance over her outbursts than if she had been a man.
The American was given three code violations for: on-court coaching, smashing her racket and verbally abusing umpire Carlos Ramos, all of which resulted in her receiving a $17,000 (£13,000) fine. "Don't worry about me", Ramos said while speaking to Portuguese newspaper Tribuna Expresso, according to The Associated Press.
When the violation was announced Williams approached Ramos to insist she never takes coaching and would rather lose than "cheat to win". Williams, clearly unhappy with the ruling, went on to berate Ramos for his judgment, repeatedly demanding that he apologize for branding her a cheater.
That anger would later cost her the game, and ultimately the match - although Osaka was clearly the better player on the night and would've probably taken out the match regardless.
Despite collecting just $62,000 between June 2017 and June 2018 due to a break to have her daughter Olympia, Williams earned $18.1 million to be the world's top-earning female athlete thanks to a lucrative endorsement portfolio.
During a changeover, Williams resumed her argument with the umpire, this time saying he was attacking her character and was a "thief". "I'm here fighting for women's rights and for women's equality". The Serbian added, "I don't think it's [the] time and place really to get into other subjects".
"They are always with their dogs behind, their team", she said. "But I'm going to continue to fight for women".
But the International Tennis Federation defended Ramos and said in a statement that his "decisions were in accordance with the relevant rules" and that he "acted at all times with professionalism and integrity".