Two weeks ago, a woman was killed at a bus stop not a quarter of a mile from my house - I'm not sure of all the details, but by the skid marks still on the road, I suspect the culprit was speeding excessively (there are plenty of morons that regard the Hagley Road as the perfect drag strip, sadly). I happen to walk by that bus stop very regularly, more often than I use DCs or indeed TT. Should I then desist in walking on pavements, as your logic would suggest? Come to think of it, I cycle by there even more often...
The fact is, everything has a risk - there is no activity that is risk free. That one activity has a higher risk than another does not mean that it is inherently dangerous, because these are very small probabilities we're talking about, and twice a very small number is still a very small number. The risk of dual carriageways or time trialling is much lower than most people would believe - but we as a species are actually rather bad in judging risk. And, as
@User30090 points out, this already low risk can be further reduced by appropriate behaviour.