How is the CAA going to get transponders on these when they are not even mandated on gliders or paragliders - both of which I and my colleagues have had near misses with this year as they don't show up on TCAS and are very difficult to see until you are right on top of them.
Fair point. Would certainly make sense to make transponders mandatory for all aircraft in all airspaces. But I think there is an additional risk when it comes to unmanned aircraft: They are just that, unmanned, so nobody sitting in there risking his own bum (which usually does the trick to make you a bit more motivated not to crash). Instead the jolly drone operator sits somewhere, detached from what's going on, piloting the thing around. Or even better, he just typed in some coordinates and sends the damn thing off into the skies, trusting the old gods and the new that his shiny toy will return eventually.