Among other things: lots of other companies (including Google) were doing the same thing, wasn’t an app for general distribution (the kid had already had his parents permission for using said app), order of magnitude a thousand people ever installed the thing.
Enforcement from Apple on FB basically came the day after they were hit with an embarrassing “Hackers can turn on your camera without you knowing it FaceTime” bug. This part is hearsay, but, IIRC, Apple only started enforcing on the dozens of other companies that were doing the same thing once legal action was threatened for uneven enforcement. (Meanwhile, the kid that I chatted with that reported things to Apple in the first place... definitely reported more than just FB.)
Enforcement from Apple on FB basically came the day after they were hit with an embarrassing “Hackers can turn on your camera without you knowing it FaceTime” bug. This part is hearsay, but, IIRC, Apple only started enforcing on the dozens of other companies that were doing the same thing once legal action was threatened for uneven enforcement. (Meanwhile, the kid that I chatted with that reported things to Apple in the first place... definitely reported more than just FB.)