They think in terms of how sturdy it needs to be and manufacturing costs, which is what they are good at, but these manufactures are not nessarily users of what they build. By the way, tanks with Internal Overflows need some thinking in advance. Internal overflows are generally placed on the inside back corner of the tank. Obviously one needs to drill a hole in the bottom of the internal overflow, and a hole on the stand as well so the plumbing can be connect from the overflow to the filter system. After drilling the hole in the tank and marking the spot where the hole in the stand needs to be drilled one then realizes that to drill the hole in the stand you are going to end up drilling right through the main supporting framework of the stand.
Lets discuss canopies.
A canopy sits on the top of the tank and usually covers or hides the lighting system. Most canopies are about 6 inches tall and sit down, slightly dropping over the edge of the tank by about 1 inch. What you want is for the canopy to extend down past the water level point in the aquarium. Most canopies have a lid that opens half of the canopy top. It does not feel good.