that capilarity is not something you can achieve overnight.

If you tell the “hey frankyspeeddetect.com isn’t doing my 500mbps” they’ll tell you to it’s an issue with that random website. ISPs and services reach out to Ookla to onboard with them because they have a network effect/mindshare of whatever you wanna call it

https://www.ookla.com/ You can see an overview of the data they collect and sell on the corporate website

I doubt they didn't collect all of that.

P.S. Now marry that huge dataset with services that Accenture provides, among others:

"In February 2025, Vice News spoke to a former Accenture employee under the condition of anonymity. His project on the WhatsApp team for Meta required him to sift through images and decide whether or not they depicted child sexual abuse, which he coped with "through a lot of substance abuse". The former employee claimed to have witnessed multiple missed opportunities to protect children, and alleged that one colleague had previously been arrested for possessing child abuse materials. In a statement, Accenture said they are "committed to helping companies keep their platforms safe through services such as content, advertising, and compliance reviews."¹

¹: https://en.wikipedia.org/wiki/Accenture

Downdetector wins because of SEO. Most people don't get there directly, they google for "is $x down" and then get sent to downdecetor. Which from my understanding works by simply showing you how many people came to their site with those search terms. They don't actually check the sites.