They modeled this — why women might see fewer STEM ads

Women see fewer advertisements about entering into science and technology professions than men do. But it’s not because companies are preferentially targeting men—rather it appears to result from the economics of ad sales.

Surprisingly, when an advertiser pays for digital ads, including postings for jobs in science, technology, engineering and mathematics (STEM), it is more expensive to get female views than male ones. As a result, ad algorithms designed to get the most bang for one’s buck consequently go for the cheaper eyeballs—men’s. New work illustrating this gap is prompting questions about how that disparity may contribute to the gender gap in science jobs.

…As a result of that optimization, however, men saw the ad 20 percent more often than women did…

Tucker ran $181 worth of advertising via Google, for example, saying she was willing to pay as much as 50 cents per click. It ended up costing 19 cents to show the ad to a man versus 20 cents to show that same ad to a woman. These investments resulted in 38,000 “impressions”—industry-speak for ad views—among men, but only about 29,000 impressions among women.

Similarly, on Twitter it cost $31 to get about 52,000 impressions for men but roughly $46 to get 66,000 impressions for women. And on Instagram it cost $1.74 to get a woman’s eyeballs on the ad but only 95 cents to get a man’s.

Here is the full Scientific American article, via Luke Froeb, and do note those differentials may vary considerably over time.  Gender issues aside, I would say this reflects a broader problem with having a very high value of time — it becomes harder to maintain a relatively high proportion of people showing you valuable things you wish to see (as opposed to people bugging you, grifting you, etc.).