Is this not just her blowing smoke to appease the PC crowd?
IMHO Bale likely got more because he was a more seasoned actor, had paid his dues, and played a larger, top-bill role.
If she used obscenity in her self-depreciation, then IMHO she comes off as misandrist, immature and jealous.
She acknowledges other motivations in her acceptance of the offer.
Agents get percentages and want to retain top clients due to the possibility of future repeat business. The market tends to dictate the pay.
When Bale was 25 he starred in a relatively obscure TV movie (Treasure Island) which probably does not generate much back end revenue. Women actors have a shorter shelf life, but in the end IMHO this is primarily due to biology, not discrimination.
If she did not want to seem “difficult” or “spoiled” back then, she may have done a good job of catching up on that now.