OK, this makes things clearer. Zoom does in fact encrypt their streams from client to client but they have easy access to the keys.
In their recent post about this question they apologize for what they admit to be an incorrect use of the phrase "end to end encryption". They base this on the existence of things like the gateways used to the regular telephone network.
It seems like an odd way to spin this. Why didn't they just state that the data is encrypted "end to end" and then leave it at that? Apple supposedly has access to the keys used to encrypt FaceTime calls but they happily involve the "end to end encryption" marketing phrase. I don't see why Zoom couldn't do the same. The way Zoom has handled this could of been a lot better.
I think the world needs a consumer standard for cryptography. Something like:
* Level 1 for the case where any eavesdropper can get the plain text.
* Level 2 for when just the provider can get the plain text.
* Level 3 for when just the users can get the plain text.
Most of what is being described as "end to end encrypted" these days is really just level 2 even in the case where the provider does not have the keys due to the fact that the provider can trivially MITM the traffic. The general public should be made aware of the distinction without having to dig into the technical details.