It bothers people that the USG virtually always wins these cases. But I think it shouldn't bother people as much as it does, for a couple of reasons:
* It's also the case that state governments win most attempts to get Title III wiretaps; in those cases, it's because getting a Title III wiretap is an expensive process that involves a shitload of paperwork, and prosecutors don't waste the time going for them unless they're sure they're going to win. It appears easier to get a FISA directive upheld, but it's not free.
* It's what you'd expect to see happen if the USG was only using FISA to conduct foreign surveillance, which, while I wouldn't take NSA's word for it, is not at all hard to believe; what is the motivation for them to set up a paper trail with the FISC of doing something else?
Yes, but that's close to being a tautology: what outlandish claim might not turn out to be true if in future startling new revelations supported it? In fact, direct access in the NSA-has-root sense is less likely in light of the PRISM slides: why file 702 orders and dicker with webco lawyers if you're able and willing to get whatever you want through some kind of back channel? Why create a Top Secret overview and training resource for Internet surveillance and apparently not mention this backdoor?
So while of course, we can't assume every covert acquisition method darkly imaginable is happening, it would also be foolish to assume that exactly what has been clearly documented so far is the full story.
Why the trouble of extra legal orders and a paper trail if the NSA already had deeper covert access? Well, the government isn't efficient and different levels can't always work together. For example, why did the DoJ use more normal procedures to get AP phone records, when the NSA already had all that data? Also, when you have a treasure trove of info obtained in illegal ways, or in ways you don't want to admit, and you want to act in ways revealing that you have that info, you can try to get it again in a second, redundant way: one that you can explain, and maybe legally rationalize.
And when nobody inside or outside your organization has the whole picture, the fact that there's some legal process for getting some info from, for example, Google, might serve as plausible cover deflecting questions about how exactly so much more info winds up in the system.
In fact, that's one possible mechanism for the PRISM slides' author thinking that the access to Google et al is so much more powerful and 'direct' than the companies' own measured response process can explain. They're each blind men feeling different parts of the elephant.
The phrasing "directly and unilaterally seize" seems exaggerated given the preponderance of current revelations and denials, but if Prism includes other not-yet-revealed acquisition methods, might still be substantially true. After all, the denials you're relying on are from company leaders who also said they've never heard of Prism.
I can believe Greenwald got overexcited in that phrasing, and trusted the slide deck (including as-yet-unreleased slides) too much. Just like perhaps Obama was a bit clumsy and overeager to reassure with his phrasing, "Nobody is listening to your telephone calls."