Both those things offer a chance of survival (just look at the number of uninjured survivors in the SFO crash a few days ago). And in a car you also have control of the speed. At 4000MPH I don't think there is any possibility of survival and the kind of mistake needed to cause an accident at those speeds is probably very small. It may not sound completely rational but I think it's something that a lot of people will think about.
Counterpoint: many people will find going 4000mph unbelievably cool (just as with planes, I suppose).
Just as in fighter jets, wouldn't 4000 MPH put a tremendous strain on the body?
It's not the speed that puts strain on the body, it's the _change_ in speed (i.e. acceleration). You are currently going ~67062 MPH around the sun and probably didn't notice. If you suddenly slowed down to 4000 MPH around the sun, you would definitely notice that. ;-). (http://curious.astro.cornell.edu/question.php?number=356)
Cars can drive around obstacles. Planes don't have set paths. But if some terrorist asshole blows up the tube, your are screwed. Heck even if it's just punctured, the compression wave of air pushing into the evacuated tube might be enough to kill you, no crash needed.
That said, it would be awesome for nonvolatile freight.
a 20 seconds full stop (as mentioned on their website) combined with compartments in the tubes which automatically close if the vacuum is breached would reduce that risk.