Sorry, but the NBA and WNBA aren't comparable. There's a vastly greater audience for the NBA, which means there's money to pay James that much but not enough to pay Bird that much.
You have a problem with it? Take it up with the fan base, or lack of one.
Why was the US Women's National Soccer Team able to reach parity with the men? Not because they were a more winning program, but because they've earned a better fan base along with that.
Quit whining and buy a WNBA ticket or jersey. That's how this will change.