EXCEPT & INTERSECT: Purpose of Passive Projection in Logical Plan
There are various things we do inside the query optimizer that don't really have a reason that we can explain externally.  The projects you see in the optimizer eventually get rewritten at the end of the optimizer to "flatten" the expressions.  So, the optimizer has things in the search that are part of how the code is implemented that may introduce extra projects that don't really do anything functionally but do allow us to stitch things together where one subtree was created in one part of the optimizer but is used later in a place where it was not originally intended.  There are some physical implementation details that can cause this to happen.  None of them matter for users in terms of plan quality (in almost any case - we have done work to make these not matter in the search).

So, I'd just wave my hand and say "you don't need to see his identification.  He can go about his business.  Move along" ;).