To be fair, I think that although not explicitly stated, the jist of the OP was concerning incidents during normal cycling on the road rather than racing/MTBing/track riding, etc where the circumstances are a little different.
Pedal strike I would class as user error in most incidences....it's why my FW is faster as a SS than as a fixie-because if I road it like an SS in fixed mode then i'd probably be off on every corner
But on the other hand, a snapped axle is pretty unforseeable in practical terms (I'm sure that you could strip the bike down between every ride and test each component in the lab...but I said in practical terms).
Not sure about the off that I reported the other day - sprinting up a hill when the crank snapped. The crank had shown no signs of damage when I fitted it a couple weeks ago (had previously had it on my old fixie for a couple of years), so you might say that it was unforseeable - an accident. But, a couple of years ago, when I got the crankset, some one had pointed out that that type had a bit of a rep for snapping years ago. Thus, if I'd headed the warning then the 'accident' wouldn't have happened.
Oh well, you pays your money and takes your chances.....but I still suspect that there are a number of incidents reported as 'accidents' which could have been avoided.