The sectors I was working were not overly busy, so the problem you highlight about UK airspace is not relevant (although I agree it is relevant for many parts of our environment). So, in the examples I experienced, the chances of me 'stepping on' someone are credible for one transmission ..... but stretching it a little to think that everytime I transmitted to a particular aircraft or two that they would also transmit to talk to me at the same time on each occasion, and that they also did so each time a relay aircraft did too.
As MOR forms now get filled in for 'Prolonged Loss of Communications (PLOC)' events, the CAA can no doubt monitor trends in terms of airspace affected, and the individual operators who experience it. This should help find out the causes of the phenomenon, and in the past has helped identify technical reasons such as 'sleeping receivers' thus allowing modifications to be put in place for the kit. The best one I heard (in terms of incredulity) was because the Captain had to leave the cockpit and answer a call of nature, and the inexperienced FO left the frequency to talk to company for a while. So whilst rare, such things do happen
Getting back to the topic, I side with Rainboe. Although the
PR effect of allowing non industry people to see what goes on has some value, I don't think it is great a benefit as them not being there during the flight, since it is removing a potential distraction. Sorry folks
Air Defence authorities in Europe are very very twitchy these days and it is only a matter of minutes in some airspace where any failed attempts to communicate will result in the interceptors getting airborne.
Industry jumpseaters on the other hand could be argued as beneficial in some cases. ATCOs, to provide education on both sides. Ops folk, to see the pressures and working practices pilots have on them. Engineers, to get the beers in on the night stop. And so on
Personally, I make the arrangements to jump seat a few times a year and always find it useful in a two way education exercise, as well as flying as P1 myself in a GA aircraft regularly. So I am reasonably familiar with the world upstairs. How about pilot visits to ATC facilities in return ?? They are like ATCOs doing fam flights .... like hens teeth.