All the words come directly from your posts. No one but you put them there.

The OPs question related to returning large volumes of data from subroutines. That inherently means that by the time the caller is running and has access to the returned data, the subroutines has ended. There can be no possibility of "shared access".

In other words, your even mentioning the term COW in response to the OPs question is entirely vacuous. Citing it as a reason why Perl copies rather than aliases the returned data, completely erroneous. Terming "not copying" as a "special case of COW", fatuous.

Continuing to defend those, is priceless.