It's not that I thought it impossible but I remembered the stretch of road and accelerating as I exited the village but not really going any faster than the car ahead of me. I still had the dash cam video and I had not deleted it despite the fact that I had bumped the camera and it was aimed a bit high (making it uninteresting as a video of the trip). I had to look at it a couple of times around the time given on the "ticket" and eventually saw the red flash of the camera going off. As you can see it is quite well hidden behind the building and in Switzerland you don't get any warning signs.
The actual end of the 50 zone is 26 seconds (less than 500 metres) further on.
A nice money spinner. The car ahead of me was doing the same speed, more or less, and I imagine nearly everyone would be somewhat over the limit there. The probably get at least one every couple of minutes. If they average 5 an hour it brings them in something like 5 million a year.
It looks as though it might be mounted on some kind of trailer so it probably gets re-located every so often.