http://www.northyorkshire.police.uk/14196
I beg to differ, said app would have found the cyclist who was missing from 1900-1030 whilst his family worried about his health.
Cycling is dangerous either made worse by traffic or rider error.
I think you are going up the wrong path here.
Firstly, cycling (as with walking or driving a car) carries some degree of risk. That does not mean that it is dangerous.
Secondly (and I do not feel overly comfortable using an actual fatal incident as an example but it is responding to your inclusion of it) the stupid app would only have helped to find the poor victim, not do anything about the incident itself.
We should and have to accept there is a degree of risk and do things to lower any risk (like not wear all black as reported in the above incident). But that is a long way from declaring an activity to be dangerous.
I for one really cannot stand this nanny state attitude. I usually leave my phone at home when out and about on my bike. I go out to get away from the world.