“I don't understand why they all seem to ignore this line in Google's TOS.”

Because not many people are good at reading and at understanding what they read.

Which, here, is this:

Gmail or Google Docs/Drive or Google Apps are not among Google’s services that “allow you to submit content”. You don’t submit anything to them. A service like YouTube, on the other hand, is, and it obviously needs such terms in order to operate.