Not sure I really understand where you're coming from. If this was a high spec car parked on double reds, does that give a motoring enthusiast any more reason to know why the driver parked it there than a regular driver? This is what you asked of cyclists.
Very possible yes in answer to that question, though if you never lock your bike then it is understandable why you may not know the answer.
I suspect that the owner locked it in a place where it was in view away from the bike shelter. If you have a high spec bike then it will be a target there. I am not excusing this anti-social behaviour, merely suggesting a reason.
It's a good case for having a low spec bike IMO.
IWAF - I love the bike planters. Perhaps we should get some of those?