I hate to say it, but this is blatant discrimination.
This is nothing like the days when the female winner at Wimbledon was paid less than the male winner because "they play only three-set matches." Everybody who wins a Diamond League title, male or female, gets the SAME money.
Do you know who is NOT getting any money? Hammer throwers and 10,000m runners, both male and female, because the Diamond League does not offer them a chance to compete. If they want "equity," offer a meet where these athletes have a chance to win $30,000 like all other track and field athletes.