[GraemeJ]

Alex: at 13:23:38
If that's the case, then the packaging and documentation is very misleading.
Alex: at 13:24:12
"Expandable storage" to me implies read and write permissions.

Unfortunately, this is an accusation that could be made of many tablet vendors.  All too often you see something like "memory/storage expandable with SD card" with never the qualification that it's read only.  It really is abut time we customers took the suppliers to task over this blatant misrepresentation of the facts. 
Of course, this isn't helped by Google deliberately limiting the write permissions, with the excuse of  'protecting' the user from a problem.  They really do treat us like idiots sometimes.