Problem as I see it, from an insider point of view, having openly had an ILETS IUR briefing at ETSI TC Lawful Interception, is that there just wasn’t really that great a demand from the majority of the police forces that the spooks were insisting were requiring Retained Data or society would end
It seemingly was a blatant grab for power, as Professor Susan Landau argues in her book “surveillance or security” she mentions that the FBI used to just see a handful of miscreants using hard-good-crypto end-to-end, and that these were easily solved by compromising one of the end terminals.
Obviously the spooks need our data, and have persuaded politicos to make broad laws, been found over-takeing nonetheless, which gave blowback so everything is now fairly well encrypted. At least the agencies are arguing the cases in parliaments/court, which is nice to see. Is the R.D. nowadays even shared with the police, or just still in a few percent of cases?