Plus the fact that many of the pilots I fly with (Germans, French, Spanish, Italian, etc) get annoyed by it and it seemingly isn't the "done thing" in their country.
That's because their country hasn't gone to the effort of setting up a Distress and Diversion (D&D) cell in their national air traffic system as has the UK.
However, in our part of the World, you need to be above 3,000' to get a decent fix from London Centre (D&D's callsign). I give my students the A5 printed sheet that D&D issue with their preferred phraseology and we generally go for the 'unsure of position' scenario, as this also tests D&D's accuracy. Even as far away as we are, it's usually quite accurate, to a mile or so.
Our local military (NAVY) generally operate fairly low so they use the local civilian LARS service for their practice PANs, on the Radar frequency. It seems they major on engine instrumentation issues 'simulated oil pressure failure' is a favourite, which our local controllers take in their stride.
I guess our having a ground service on 121.5, being unique in the World might seem a bit anachronistic in this day and age. Bear in mind it is run by the military, originally for the military. Within the UK, my first port of call if I had a problem airborne would be the unit I'm already communicating with; I never fly without having at least a basic service from someone. However, a few years ago I flew to the Faroes, over a lot of dark grey, very empty North Atlantic and we had 121.5 on box 2, just in case...
TOO