There is absolutely no reason why the public at large can't know that some three letter agency is legally forcing a company to provide information with a national security letter. The public knowing that this is happening doesn't divulge any useful information to anyone. The fact that free speech is in fact being trounced in the US is really freaking gross to me.
I don't disagree that it can change behavior, but surely many or most of these nefarious actors must already assume that uploading illegal materials to Apple or Google, whether they claim E2EE or not, is a risk? See for example Apple's ditched efforts to scan and flag CSAM material on-device.
My assumption has been that the real bad guys use their own infrastructure attached to anonymous access methods like Tor, or using anonymous file sharing accounts that can't be tied to an iPhone's serial number. Maybe that's not true?
Offering transparency in these areas may help to understand whether the government is really doing this to arrest criminals, or just to have unfettered access to everyone's data.
Literally any bad actor with half a brain cell assumes every large american tech company has been served a NSL. Disallowing them from disclosing they received one seems pretty pointless and only done to prevent bad optics and public opinion
It's not naive. I can definitely see value in a two-tier warrant system. The first (and normal one), just like a physical warrant: you know you're being searched. The second, and it is much harder to get: a covert warrant, more like a wiretap.
The oversight body is the legislature. The judiciary has no ability to provide oversight. The judiciary cannot act on it's own. It cannot conduct investigations. It can only act on cases and motions within those cases. The two ideas you've presented do not have anything to do with eachother.