I work in telecom and we interface with large carriers like AT&T, Verizon, etc. We use headless browsers to automate processes using their 15-year-old admin portals, since the carriers simply refuse to provide an API, or one that works acceptably.

Thankfully they're also so technologically slow that they never change the websites or do any kind of headless detection. Its works, and allows us to offer automated [process] to our customers, but it seems so fragile. Just give us a damn API.