When measuring objects, one generally works from the ground up. This technique seems to have its origins in mathematics, where Cartesian coordinates are noted as (x,y).
It also makes the most sense when constructing objects. To build a building you first make the ground plan and then work your way up, to do it any other way would be needlessly complicated in any environment that involves gravity. The addition of depth as a z-axis in an (x,y,z)-coordinate system also is the most logical two-dimensional representation of three-dimensional measurements. Since the representation is flat, width x height is first found to which the non-existing depth is then added.
Since most measurements are used in construction and most construction is based on math, the notation of measurements is generally based on math. Thus either LxWxH or LxHxD are the most commonly used notational systems.
The only significant professional field that consistently does this the other way around is the arts. When measuring art, the standard is height x width and even height x width x length.
One could assume that this is simply because artists are a strange folk that like to follow their own rules, yet this makes little sense as all computer programs used in the graphic sector also work with standard Cartesian coordinates, as do most building tools.
The reason instead seems to lie with those describing the works, not the people who created them. Few art historians have real experience in construction. Since they generally don't know how the objects came to be, they relate to those objects in the same way they relate to their own body; height is the most important, then comes width and perhaps depth is added if its worth mentioning.
Therefore, art is measured in a different way from almost any other object simply due to the working field treating objects as if they materialised from nothing.
