There are very few countries with as broad a constitutional protection for speech as the United States.
The problem now is that we have a government which has discovered effective work arounds for those protections. The government can pressure intermediaries who don't have the right incentives to vigorously defend their users by going to court, and then the actual targets of First Amendment violations never encounter a court proceeding in which to raise a constitutional defense, they just get cut off by the "private" service provider. The government can try to gag everyone involved so that, again, the people whose privacy or right to anonymous speech is invaded are never told and so they can't challenge the constitutionality of the invasion.
If any of this could be challenged in a public court proceeding there is a good chance the courts would find it unconstitutional. That's why they're twisting themselves into such contortions to make sure that never happens.
With "Parallel Construction", we see an explicit attempt to avoid Judicial Review, with the DEA mysteriously dropping charges whenever a case goes to court. Which is bad, as we've now trusted the constitution entirely to Judicial Review - congress has washed their hands of a responsibility to uphold it.
I suppose you could argue that the DEA knows it's unconstitutional and is willfully violating, and that raises even more troubling questions.
I also wish the constitutionality of FISC court itself could be challenged, as I think it clearly doesn't fall under article 3. But I have no idea how this would be done.
Some countries, like Germany, have Supreme Courts with more interventionist abilities, and more recourse against willful violations.
The problem now is that we have a government which has discovered effective work arounds for those protections. The government can pressure intermediaries who don't have the right incentives to vigorously defend their users by going to court, and then the actual targets of First Amendment violations never encounter a court proceeding in which to raise a constitutional defense, they just get cut off by the "private" service provider. The government can try to gag everyone involved so that, again, the people whose privacy or right to anonymous speech is invaded are never told and so they can't challenge the constitutionality of the invasion.
If any of this could be challenged in a public court proceeding there is a good chance the courts would find it unconstitutional. That's why they're twisting themselves into such contortions to make sure that never happens.