You may continue to hold that opinion, but I see no reason to trust denials by either the gov't or by Google/Facebook/et al. "Unfettered access" is easy to deny, but it may be the case that what the gov't has amounts to the same thing, or is effectively unfettered access. The gov't officials involved have little incentive to tell the truth, and a large incentive to conceal their activities. The corporate parties may be compelled to lie, or at least be unable to tell the truth (under duress).

>Dragnet surveillance techniques such as tapping fiber is a different issue.

A single program of many. Don't confuse gov't denials concerning one activity under one program, as proof that the gov't isn't conducting that activity under some other program by another name. Also, gov't officials have been caught in outright lies James Clapper, for example.

>I'm sure they have methods for downloading phone data that are hard to detect and would look like malware if someone happened to detect it.

Phones report their users' every activity, this has been discussed here and on the internet at large, at length, several times over the past few years. Most recently was the disclosure related to Motorola phones which is still on the front page. https://news.ycombinator.com/item?id=5973282