I did a search and didn't find anything about this.

A newly created box object is not the same as 1 grid unit. Shouldn't I be able to drop the box and change scale and each scale integer is same as one grid in the viewport?

A newly added box node is 1 grid unit (1,1,1) its just positioned about the centroid, so if you want it to be from 0,0,0 to 1,1,1 then drop down a matchsize node and change all the justify's to min