I have a feeling that none of the comments here come from anyone (other than Bob Carnie) who has actually seen a Jeff Wall photograph.
The couple that I have seen are spectacular - not for everyone's taste - but really intriguing and impressive.
The 2 metre by 2.5 metre size of this one means that it is one of his mid-size pieces, and unlike just about anyone else's work I have seen, the large size is beneficial, and integral to the work.
You certainly cannot get much of an appreciation of his work from small, internet images.
I'd suggest seeing some of his work, before you pass judgment.
It could be the very definition of spectacular and still not make sense to me at that price. I understand what you're saying but I think it's tangential to a discussion of the nature of monetary valuation.