While Im sorry that you got reported for driving around in your car looking for your grandmother's new home I don't see it in the same light as locking a large dog in a small confined space unnecesarily (sp?, sorry) for a relatively long period of time.
Well, I hope you’ll forgive me if I do see a parallel. You see, I assume that, generally speaking, people aren’t burglars casing a joint, or likely animal abusers.
I’ll assume the driver is lost or having trouble finding somewhere, and that the animal owner knows his dog better than me and has good reason to be doing what he’s doing – especially in the absence of any other symptoms like verbal abuse, under-nourishment, a poor coat, etc. Was there, for example a baby in the car the OP couldn’t see from distance? Has the dog owner previously had trouble with, and been problematically distracted by, the animal over-excited by car travel?
I also only ever see those cages used after a walk in the country or park i.e. when’s the dog is dirty or muddy. I’d also think they’d be useful if you have an excitable, and therefore distractive, dog.
I take the height issue on board, though we don't know about the dog or the vehicle in this case.
I’d agree there’s sometimes a tricky line between being a responsible citizen and (the equivalent of) a net-curtain twitching busybody and this is, conceivably, one of those situations. But I’d be very careful about crossing the line.