alt Hacker NewsFor one, GrapheneOS is open source, unlike EncroChat which was a shady proprietary app distributed on shady modified smartphones.
GrapheneOS also doesn't have any custom messengers or other services which could potentially be monitored. It's very easy to check where your phone is sending requests, and if Graphene was secretly MITMing all of your traffic it would be discovered within days.
Since more than a decade that MITM is not a mass event. It is a targeted event for selected users which are scored as having a low chance of discovering anomalous traffic. It first (publicly) started by government authorities sending fake updates to operating systems which then weaken the target machines or straight up RAT them.
Same case here.