I suspect that everybody is right - there are several reasons why you don't get a response. Paranoia, which is fair enough - this is Elite Dangerous right? Also, as a pilot, SC'ing does keep you fairly busy if you want to have a quick and efficient journey (and who doesn't want that, really). And of course the difficulty of interrupting your thought processes to figure out how to work the darn comms system - I'm sure it will become easier as we all get to practice it but right now it is confusing - it takes time to locate and target and so on.
Anyway, I hope that everybody keeps trying and doesn't just give up in frustration. It's nice to see a greeting even if we are unable to respond, for whatever reason. For myself, I have yet to be able to successfully respond - not for lack of trying but usually because I just haven't been quick enough to get to it before some other urgent attention is needed elsewhere - or the other Cmdr shoots off.