I hope Kelly Price is genuinely safe! And thank you for calling this out--I'd heard about both cases, but it made no sense to me that Petito would get so much coverage and Price so little.

I think you picked the wrong graph to illustrate the problem, though. When someone goes missing, the bottom line is: do they get found, and found quickly? It doesn't matter how many people are missing, which is what your graph shows. It matters that whoever they are, they're found promptly.

Unsurprisingly, there's a huge disparity, according to a study of missing children cases in New York. Here's their Figure 2 (and you can get to their paper from this link): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6312271/figure/pone.0207742.g002/

It shows that when cases get tough, it takes way longer for black children to be found than nonblack: after about six days, three quarters of nonblack children are found, but it takes three times longer to find the same fraction of black children. Most of the cases are runaways, but this is still unconscionable. We have to do much, much better at finding missing black children. It doesn't really matter what the cause is--we just have to do better.

What your graph shows is largely unrelated to the media attention or recovery issue. It shows that a lot of black people go missing. If anything, this would be a reason for the media to ignore it: they focus on novelty, and per capita it's less novel. (Still a terrible reason, but that's media for you.)

So, yes, it's true, a lot of black people go missing. It's a serious problem that deserves serious attention. It's not (directly) the media's fault, though. What you need to support your thesis is what van de Rijt provides.