Michelle Williams. (Mario Anzuoni/Reuters)

All the money in the world, but not enough to pay women equally.

This week, it was revealed that four-time Oscar-nominated actress Michelle Williams received less than one-tenth of 1 percent of co-star Mark Wahlberg's pay to reshoot scenes for "All the Money in the World," a thriller released Christmas Day. The reshoots themselves were necessary to cut alleged sexual abuser Kevin Spacey out of the film, with Christopher Plummer replacing him.

According to an exclusive report from USA Today, Williams was paid a per diem of $80 for 10 days of added work. Wahlberg received the same — plus $1.5 million more.

Obviously, the disparity is outrageous. The revelations are especially staggering coming on the heels of the #TimesUp protest at the Golden Globes just days ago, itself an expression of the #MeToo movement that has for months publicized rampant gender inequity and sexual harassment in Hollywood and other industries.

One thing this moment of reckoning has done is open the eyes of observers — men and women alike — to the imbalances that make possible such egregious offenses against women. Williams said as much herself in a profile published the day after her pay discrepancy was revealed: "Sexual harassment is a branch on the tree, and the tree is the power imbalance."

So what are the other branches? Williams's predicament highlights a few.

The most obvious spans industries and sectors of life: the fact that women's work is undervalued relative to men's. In Hollywood, a movie's female headliner often gets paid millions less than her male co-star. In less glamorous industries, estimates of the wage gap range from 77 to 91 cents on the dollar. And closer to home, labor seen as "women's work," such as cleaning or caregiving, is often compensated poorly — if it's seen as worthy of notice at all.

And then there's the question of work opportunities. The profile of Williams also noted that "All the Money in the World" finally put her in a leading role after a decade and a half of work; she was neither love interest nor kindly wife, but a main character. Knowing that the movie risked being shelved, Williams offered to forgo her salary (and Thanksgiving vacation) to ensure that the reshoots got done in time. Yes, that was a choice she made. But if there were more opportunities for women, perhaps Williams wouldn't have been put in the position of gifting away her pay for one shot at success.

Harder to sort out are those places where the branches of gendered assumptions and work intertwine. There is a long-standing notion that women are expected to sacrifice and not complain for the good of the team. Williams volunteered to work free so the movie could be finished; Wahlberg, obviously, did not. Think of how this power imbalance plays out in cases of harassment: Women are pressured, explicitly or implicitly, to stand down and keep quiet rather than ruin the careers of their abusers. Men? Well, not so much.

It's difficult to blame the producers of "All the Money in the World" for accepting Williams's offer to sacrifice for the greater good. Which time- and resource-crunched manager, offered a way to save millions of dollars and jump-start a production, would turn it down? The better question to ask, however, is why it's so often women who make the offer and shoulder the results.

How do we cut down this tree? It's more complicated than it sounds. Some would say that it's the woman's job to speak up, to not allow herself to be taken advantage of, to negotiate as hard as a man would. But it's also her employers' and our society's jobs to not label her difficult or angry when she does. Women who ask for more are still seen as "intimidating" and "aggressive," research shows, and are flagged as hard to work with. Men who negotiate are seen as savvy.

Most important, we must remember that the tree's roots are deep. Sexism and its resulting power imbalances are not just about one incident of misaligned pay or a single come-on gone bad (despite what actress Catherine Deneuve might say). These are simply examples of how the world works when power, historically and by design, is tilted toward men. Remaining aware and outspoken reminds us to whittle away at the source whenever and however we can.

Many Hollywood stars, male and female, have spoken out in Williams's defense. The Screen Actors Guild is investigating whether "All the Money in the World" broke any contract rules. We're more aware and more mobilized than ever, and each new incident seems like a hatchet blow against the trunk of a twisted tree. The tree may never fully come down, but we should hit as hard as we can.