You have it correct. Nearly every major US provider maintains some sort of online interface for law enforcement to submit requests. The level of information provided via these means varies, but they are obligated to respond to legitimate requests with wharever data they have on hand.
Dont like it? Go with a security-minded service like signal. Or, better yet, something totally severless and open source.
I don't use WhatsApp. But if they have an official backdoor, then it's not really e2e encrypted. Until now I thought, at least the official statement was, WhatsApp is truly e2e encrypted. Just that.
The end-to-end refers there to the hand-held device, not the peers' brains. The backdoor will then simply be in the hand-held device, intercepting the data meant to be displayed by the WhatsApp application.
Dont like it? Go with a security-minded service like signal. Or, better yet, something totally severless and open source.