Imagine a film set in Toronto where every single character, from the lead actors to the incidental bitplayers, have a New York accent - for no apparent good reason. You might think it was rather bizarre. The question, in fact, might drive you so insane that you lose all track of the plot as you try to fathom the answer. This was the experience I had as a Scottish person watching 'Unleashed'. I actually spent the first hour of the film assuming it was set in London - after all the streets were peppered with cockney gangsters and everyone had an east end accent. It was only when I started recognising certain unmistakable Glasgow landmarks, and when Morgan Freeman's character makes reference to the "best supermarket in Glasgow" that I realsied to my shock that the film was set in Scotland.
You're right, there's not a single Scottish accent in the film. I loved 'Unleashed', but I have to admit this apsect of it kind of ruined it for me as i spend the final half hour thinking "Why does everyone have a London accent? If everyone has a London accent, why didn't they just set the damn thing in London?"
If anyone has an explanation for this bizarre Hollywood quirk then please, please enlighten me.