Aside from the lack of E2EE, why is Telegram not trustworthy?
A lot of privacy guides suggest avoiding Telegram. I understand that in its default mode there's no E2EE (and no E2EE for groups at all).
If people I know don't wanttko use Signal, isn't Telegram the lesser evil given it's nicer privacy policy (than other popular ones)?
I find Telegram to be at least as trustworthy as Signal. Signal has a lot of red/orange flags that bother me. For example, Telegram is not based in the United States, whereas Signal is.
An app designed by US company doesn't represent anything related to security.
The founder of telegram always complains that the FBI has access to signal, apple and other related chat apps.
He suggests to use private chat, if it is confidential. The message transactions happens between peer to peer and it doesn't go to the server. He was claiming all the privacy feature that you get from signal is the almost same as private chat. Signal stil uses the server.
The server’s trustworthiness does not matter for Signal. The app is designed to work securely regardless of the server. Moreover, even if the server software is open source, you cannot be sure that they run the same code that they publish.