I said nothing about the gag order attached to an NSL. They are a violation of First Amendment rights and adhere to basically none of the checks the courts have

I said nothing about the gag order attached to an NSL. They are a violation of First Amendment rights and adhere to basically none of the checks the courts have put on gag orders in the past. The reason this hasn't been rectified is exactly as you point out: their very nature helps eliminate most legal challenges to them. But that's not what I was talking about. An NSL is an administrative subpoena. It can compel you to turn over metadata about communications, for instance, which is absolutely a Fourth Amendment violation with what you can discern from modern "meta"data, but it can't compel you to turn over the content of those communications, and it certainly can't compel you to, for instance, alter the software on your customer's phone to allow easy intercept of all future communications.