When I set it to default items, it won't salvage tools or special items for example, but an option to have all item types at once be auto-salvaged would be nice :)
That's odd, it should be salvaging all item types currently, based on how you have set each category up. It's never actually set to default items, for example. The "Item Type" dropdown only indicates which group of settings you are currently looking at.
As an example if you set the item type to default items and change the rarity to epic, then change the item type to tools and change the rarity to epic again, then hit save. The result should be that both default items and tools of epic quality or lower will be autosalvaged.
If that's not working I may need to take a look at your save and see if there's anything interering with the auto salvage.