All the general arrangement drawings I have seen were drawn to scale.
There's a rather famous one that is to scale but contains a famous error duplicated in many, many models. But it's off topic.
I've seen railroad GA drawings that were laughably out of scale. Lionelish. But perhaps those were:
Is it possible that someone has confused 'general arrangement' drawings with what is typically called 'equipment diagrams,' those small (usually about 5" x 11") drawings collected together in a book given basic information about all the currently used freight cars for a particular railroad?
The someone may have been a model manufacturer at one time or another :-)
