The #DeleteUber campaign got another boost this weekend after a former Uber engineer wrote in an essay that she had reported incidents of sexual harassment at the company, and that the company had protected the alleged harasser. Uber CEO Travis Kalanick pledged to immediately look into the incident, hiring former Attorney General Eric Holder to investigate the allegations.

This was not the first round of bad press for Uber in recent weeks. In late January, Uber turned off surge pricing after taxi drivers halted work at JFK airport to protest a President Trump’s executive order on immigration, a move that opponents said helped the company profit from a drivers’ strike. And earlier this month, Kalanick stepped down from a position on President Trump’s economic advisory council after employees and consumers protested his involvement with the administration.

In each of these instances, #DeleteUber has caught on. But while 200,000 people may have ditched the app, changing consumer behavior en masse is difficult. Uber is still the most popular ride-sharing app out there by a longshot, despite years of headline-making controversies.

“A lot of people will say they want to support a boycott—they may be ideologically aligned with a boycott—but they have a harder time following through with it,” said Brayden King, a professor at Northwestern’s Kellogg School of Management. “Most of the time, what we find is that consumers don’t actually follow through with boycotts.”

Uber is, of course, far from the only company targeted by activists. There was the campaign to boycott The Gap after the Rana Plaza factory collapsed in Bangladesh in 2013.  There’s an ongoing campaign to get consumers to boycott Driscoll’s, the world’s largest distributor of berries. The #GrabYourWallet campaign is trying to get consumers to boycott brands associated with the Trump family. And boycotts aren’t solely a tactic of the left: Conservatives launched an #AnywhereButTarget campaign to get consumers to avoid the chain after the company said it encouraged transgender team members to use whichever bathroom they preferred.

Yet these boycotts are rarely effective in getting most consumers to change their behavior. That’s because consumers are habitual, King said, and have a hard time changing their buying actions. Most people are primarily concerned with quality and price, not ethics. And shopping isn’t something that’s particularly public. People can quietly take an Uber or buy t-shirts made in a sweatshop, even if they know their friends would excoriate them for it.

“Most of the time we consume in private, we’re not held accountable for our actions,” King said.  

Americans are willing to sacrifice their money for issues they care about—they gave $358 billion to charity in 2014. But there’s a difference between giving to charity and changing shopping behavior to support a cause, said Julie Irwin, a management professor at the University of Texas-Austin.

“My research shows over and over again that it’s hard for people to make these judgments,” she told me. “It’s really stressful to think about these issues, you might be in a hurry—the marketplace is not super compatible with ethical judgment.”

Consumers are conditioned to be smart shoppers, and so want to pay the lowest price for goods, she said. “Many of us will go protests, we’ll give to charity, but when we’re shopping, it just isn’t how we think,” she said.

For example, Irwin cares about the environmental impact humans are having on the planet, as she wrote in a 2015 article for Harvard Business Review. But when she traveled to Disneyland and was offered the “green package,” which meant the hotel would not wash her towels or tidy her room to save water, she turned it down. “People both want to be ethical and they want to ignore ethics,” she wrote.

Of course, there have been a lot of successful boycotts throughout history. Most famously, the United Farm Workers’ grape boycott in the 1960s resulted in improved working conditions for farm workers. It’s harder today, though, Irwin said. Thanks to the internet, there’s a lot more information out there about products, and about ethical decisions. “There are so many people shouting on social media about something,” Irwin said.

There’s no longer just one company to boycott or one company to patronize. Everyday buying decisions become fraught with larger implications, and many people don’t have the fortitude to keep track of them all and shop accordingly. “People get fatigued,” she said.

For activists, this may not be the problem it initially seems. According to research from King, at Northwestern, it might not matter if boycotts never go mainstream. Most companies are worried enough about their reputations that they’ll change their behavior, even if the number of people partaking in the boycott is rather small. When boycotts receive national media attention—as 25 percent of boycotts do, King says,—a company will react, even if sales aren’t affected. For example, in 1992, when Texas policemen called for a boycott to Ice-T’s song, “Cop Killer,” people were curious about the album and sales rose, King said. But Warner Brothers didn’t like the effect the album was having on its brand, so it pulled the album, “Body Count,” from shelves.

“Companies realize boycotts are not troublesome because [of] sales—they worry about the media attention they create,” he said.

Boycotts can make companies seem politically toxic; research shows that when a company has been boycotted by activists, politicians are more likely to return a company’s campaign donations, and those companies are less likely in the future to receive government contracts, King said. Companies with bad reputations may have a harder time recruiting high-quality employees. A company’s negative reputation may take a toll on employees’ personal lives; King has talked to CEOs who say they get tired of having to explain their company’s policies to curious people at community dinners or events. “It takes years and years to build a reputation, it takes one bad event to completely destroy that reputation,” King said.

This means, King says, that even if people are still largely using Uber, the company may have some trouble down the line if its brand keeps getting criticized nationally. One notable effect: King attributes the continued presence of Lyft primarily to Uber’s repeated missteps. Sales may not be particularly affected. But Uber’s reputation takes a hit every time a new controversy emerges and sends the #DeleteUber hashtag trends once again. And a good reputation is one of the most valuable things a company has.