Probably they are employed at companies who are themselves violating GPL and have seen this being done there.
He just refused to believe that software licenses were real. That and I dont think he could actually code anything from scratch without stealing large swaths of code from open source repositories.
Ftfy.
In companies with mature software processes there is always tooling that will block a release if it finds unacceptable license. To me it looks like TikTok hasn't properly invested in tooling and this somehow slipped.
This doesn't protect anybody against illegal copy-pasta by ignorant/irresponsible devs, though.
As a result of this, I think there's this mass misunderstanding of how licenses work in the software engineering field.
[1] With the exception of AGPL if I understand correctly.