Sending PDFs on event notifications and reciepts - disabling
Turns out that there is an additional setting on CiviContribute Component Settings that appears to override the Misc System Settings which only becomes apparent when you turn on tax/invoicing.
(/civicrm/admin/setting/preferences/contribute?reset=1)

"Automatically email invoice when user purchases online"

This is somewhat confusing.

Perhaps we should change the labels and descriptions such that it's more clear what these options mean.


Amend the setting on System->Misc page to reference the fact it might be overridden
Change the wording of Civicontribute settings so that it references that by "email invoice" it means attach a pdf (and will override what is set in 1).