It's a mind set. Here is a documented example. But I no longer have the link. In WW II a B-29 made an emergency landing in Russia when it ran low on fuel during a bombing run to Japan.
The Russians eventually gave the B-29 back, but not before taking it apart and blueprinting it. They then made their own versions of it. These aircraft looked exactly like the Boeings, but were actually slightly bigger. The reason, when they made their aircraft they took the American specs, converted them to metric and then rounded the fractional metric measurements up to the nearest full millimeter. Hense the increase in size.
I suspect that more of the foreign copy cats do this than we realize.
Joe