【Esther Moser】

Facebook,Esther Moser Google, and Twitter are facing a lot of difficult questions over their ad policies after it came to light this week that all three companies allowed advertisers to run targeted ads based on hate speech.

Though the circumstances around each case were slightly different, each one was the result of a mostly-automated system that allowed advertisers to buy ads targeted toward people likely to respond to hate speech and other offensive language.

And, in each case, the companies claimed that it wasn't supposed to happen. Yet the fact that media outlets were able to buy ads for these terms so easily, and in such quick succession, highlights how little these companies -- who count themselves among the biggest tech giants -- were doing to prevent this from happening in the first place.

In Facebook's case, ProPublica reporters found that they could buy ads targeting people who were likely to respond to "Jew haters" and other anti-Semitic words and phrases. Soon after, BuzzFeedreported that it was able to buy Google search ads based on racist and anti-Semitic search queries, including "Black people ruin everything."

Then, The Daily Beastreported that it was able to buy ads on Twitter targeting people who were "likely to respond to" terms like "Nazi" and a derogatory word typically aimed at undocumented Mexicans living in the United States.

To be clear, all three companies have policies that prohibit hate speech. Facebook and Twitter ban or suspend people who promote hate speech. Google has a similar policy in place for developers and others who use its platforms.

Despite this, all three allowed ads to be purchased based on hate speech that would otherwise be banned from their platforms. That says far more about each company's priorities than the policies themselves -- or their apologies after fact.

In all three cases, the companies were quick to apologize and say that these cases were the exception, rather the rule.

"We prohibit advertisers from discriminating against people based on religion and other attributes. However, there are times where content is surfaced on our platform that violates our standards," Facebook's Director of Product Management Rob Leathern said in a statement. (Later, the company announced that it was removing the feature that allows users' self-reported interests to be listed in advertising categories entirely.)

Google's SVP of Ads, Sridhar Ramaswamy, also apologized, saying: "Our goal is to prevent our keyword suggestions tool from making offensive suggestions, and to stop any offensive ads appearing."

Similarly, a Twitter spokesperson said that the offensive terms in question "have been blacklisted for several years" and that the company is "looking into" why their filters didn't prevent the ad campaign from running.

While these companies are right to take this seriously, it's difficult to accept their explanations when this is a problem that could be avoided relatively easily. Blocking hate speech from advertising platforms should not be a difficult problem for these companies, which employ many of the industry's top engineers, to solve.

Facebook is working on brain-controlled computers. Google practically invented self-driving cars. Twitter's CEO is one of the most lionized founders in tech (and one who has claimed that fixing harassment and hate speech is a top priority.)

Again, the fact that this hasn't been solved yet says more about these companies' priorities than anything else.

As others have pointed out, what all of these companies also have in common is that their entire business depends on a steady flow of ad revenue. Making easy-to-use tools that allow anyone to buy ads in just a few clicks is core to everything they do.

And while none of these companies want to be seen as profiting off the vile hate speech meant to appeal to the internet's basest trolls, it's not difficult to see how advertising policies could face less scrutiny than, say, those applied to users or developers.

That needs to change. The time for lame excuses and half-hearted apologies is over. The biggest tech companies in the world are more than capable of fixing this. It's time that they do.