Well, the idea was that you would only ask to export that particular key if it was defined in p in the first place. Further to that, since you are exporting from p to q, if something is not in q, then it should be created. After all, the idea is to move data from p to q. If q was an empty hash, clearly nothing would ever be inserted into it.

Also, as best as I can tell, reading from a hash at the root level does not create keys, even when using hash slices.

The idea for schlep() is to move data simply and efficiently from one or more hashes into a single hash, remapping as required since the two namespaces likely differ to some degree.