It happened to me once that I chained my bike to a stairway railing, certainly not moveable. When I returned, my bike was gone... actually the railing was gone. It was about to be replaced, so the construction workers had cut away the railing. They had placed my bike carefully a few meters away, though it wasn't tied to anything any more, as the railing was removed :).
Ten years or so ago I recall a story about some guys in Eugene unbolting an entire rack full of bikes from the asphalt and loading it into a truck. Can't find the story now.
The bigger, the easier to get away with it from a social perspective--they could look more like people on official construction business.
You can steal anything as long as you steal it with a service truck or a rollback and wear a reflective vest while you do it.
Solution: a device that takes a closeup hi-res photo of the remover.
If I recall correctly, they were dressed like ODOT workers to appear official.
This was also a persistent urban legend in Cambridge, England in the early 90s. I'm not sure how much I believe it, bikes were/are easy enough to steal as it is