If one on my team wrote something that was confused by spaces like that I'd bounce it back before QA even got to see it.
Just before I left, the problem ws that everything was being outsourced and offshored, so that it could be done as cheaply as possible.
So the offshore company would write the code as cheaply as possible, and couldn't care less if the system could recognise a post code without the spaces.
(Don't even get me started on people writing code that only recognised the US date format mm/dd/yyyy



)
All too often, when I raised a bug like the system refusing to accept valid postcodes without a space, the software developers would look at the specification, and would refuse to fix the bug unless the specification contained an explicit statement "..
the system must be able to recognise post codes that are typed in without a space...".
Or they would fix the bug if we bunged them a bit more money.