Apparently "Simple Delivery" is only currently available in the UKand presumably eBay will see how it goes in the UK before rolling it out in other countries.
If you want to do your own shipping you now have to change the listing every single time you re-list the item to reflect this and also reset the handling time. Apparently there is no way to change your settings to remain opted out and the only way to opt out is to do so for each and every listing, every time the item is re-listed.
Also with this new system it seems to sometimes re-list items that are "Collection only" with a shipping charge which you then have to change back to "Collection only". Obviously there is normally a reason why an item is listed as "Collection only" such as being too baulky to send in the mail.