You have a piece of paper, America has a piece of paper, but neither of them are worth anything if the protections to declare are not upheld. The repurcussions for violating those protections are more trivial than traffic violations.
The US has laws that should have prevented people from lying to Congress about PRISM, but it happened anyway.
Your Article 8 protections only matter as much as they're enforced and respected by the government. If Article 8 was the defense you imagine it to be, then the Investigatory Powers Bill wouldn't have passed in the first place.
It's very hard for me to square the text of Article 8 with a bill that allows warrantless access of every single IP address you visit. If that's consistent with the government's interpretation of the text, then it doesn't sound to me like the text is doing its job.
