Except....they already provide "Poof! It's gone" with OSX, so they can't be that worried about it...and it has the safety feature of requiring a deliberate 'two keys depressed' action. I'm just looking for continuity of convenience features from one system to another.
Actually the OS X functionalities are moving toward those in iOS not the other way around. In other words, I think what we will see in Maverick (later this month?) will be even more like what we are seeing in iOS 7.
My guess is that most people send email to trash by clicking on Delete, providing the safety aspect you mention.
I would guess your guess is pretty accurate. At least I almost always click on delete then if and when the Trash folder gets too big before it is automatically emptied, I will go there, select any message, press Command+A, then click the Delete icon to clean house.
And, isn't this why we should back-up our data?
All of my email accounts are IMAP and the trash is saved on the server, not on my computer. I know the IMAP servers are backed up, but I for one would have no clue how to retrieve a file from one of those backups. So that backup really doesn't do me any good unless it is needed to provide recovery in the event of a failure of the IMAP server.
