I have wondered the same thingNot exactly on the subject here but concern the heat protection one. If the codes ask for 16 or 18 inches from the stove to combusting materials, it's probably to protect the combustible materials from burning down or avoid it as much as possible.
How stoves like my Heritage having 4 combusting wood handles located very close to the stove can meet the same safety codes ?
Maybe a curious question but I have it in my head from a long time ! Thanks