How long before the prices come down enough and the technology is suitably sophisticated that the big races issue all runners with a gps unit and has wifi receivers round the course so all runners can be located at all times?
even if they can do it, it is overkill.
a solution to a problem that doesn't really exist.
Not true. It might appear like that on the surface, like most cities, but it isn't. It's the place where passers-by lift buses off cyclists, stand in their front gardens with hoses on hot Marathon days and turn up voluntarily to help clean up after riots.