The reason trash is not sorted right now is because that would require storing deletion date on items. This is not a huge deal, but seemed kind of unnecessary. I guess it’s true that it can be hard to locate a recently deleted item in a big pile of trash That said, similar data fields have already been added for data syncing purposes, so it should be possible to finally sort Trash by deletion date.
Undo is more tricky, as it requires to store the place where the item was deleted from - either a list, or a project (which might get deleted as well). I don’t think undo/undelete is worth the trouble considering how infrequently it will be used.