Even if the system behaved like PRISM such that chat apps and network operators used the client-side apps to scan for keywords on specific accounts and reported back, similar to how child porn filters might work today, which would be an end-run around e2e encryption but not require transmission of every message, the risk is that the system itself might end up in a compromised state where any nation could request records of any device and suggest that national security is the reason. And that assumes the system is designed securely using asymmetric encryption and unleaked keys, there’s still data storage on the other end to worry about. I get it though, it’s possible to dive down a rabbit hole where you continuously think up technological ways that this could happen securely and prevent attack vectors as they come up. The point I’m trying to make is that it is indeed a political problem to prevent technology from being abused. Making zero exceptions is still more technologically and politically secure than making even one exception for trusted government use unless you trust every government.