Well, no. If an OB insists on a C-section because a late-pregnancy ultrasound showed a 3x nuchal cord, and upon removing the baby she has no nuchal cord, you can pretty much define that C-section as unnecessary, at least in retrospect. Same if a C-section is given for fetal macrosamia according to ultrasound (which is a very dubious method of determining fetal size), and the baby emerges at 6 pounds soaking wet.
I realise that's not exactly the point of your post, but there are definitely times when it can be seen a C-section was unwarranted. In some of those cases it may have been justifiable at the time; in some, not so much. Heck, there's pretty solid evidence that a lot of OBs schedule C-sections for convenience, and that is definitely medically unnecessary.
But yes, I agree with your point that we don't need to jump down C-section mothers' throats to make sure they're really "worthy" of our pity/support/compassion/approval because the C-section was "really" necessary. That's a nasty attitude.
Having had late-term pre-e last time, yeah; I've never really thought of myself as high-risk exactly. It's something to watch out for, but then, my MWs picked it up just dandy last time when there was no particular reason to suspect it, so they were clearly aware of the possibility even without a history. I didn't transfer, either; at least, I risked out of HB and had to be induced in hospital, but my midwife provided my care throughout. My current midwife has a similar continuity-of-care philosophy, so I imagine she'd do the same.