I am not sure how window film escaped the signage by-laws.
AoD
It didn't.
The by-law regulates "window signs", which are defined as "a sign erected, painted, attached, etched, inscribed, or projected onto the inside or outside of any part of a window in a wall, a sign located within or in place of the glass of a window, or any other sign erected or displayed in a manner so as to be visible through the window from the exterior of the building but does not include a sign that forms part of a window display." (There are also controls on electronic window signs.)
Outside of residential areas, "first party" window signs (i.e. signs directing attention to goods and services available on the premises) are automatically allowed, as long as the signs do not take up more than 25% of the window area (excluding the frame), among other controls. Most window film signs blatantly exceed this 25% limit.
The terms "signs" and "sign copy" are both very broadly defined, so just about all kinds of graphics (even the Shoppers Drug Mart stock images of happy people) would appear to constitute signs.
Yet enforcement, or even concern, seems to be lacking.