6) EROI has political elements. One example: in strip mining, how do you categorize tasks such as putting overburden back into the hole, compacting dirt, landscaping etc.? The energy inputs needed for such processes are not a physical requirement of mining the coal and harvesting its energy. They're a political requirement. They aren't strictly *necessary*, except within the context of certain political arrangements.
This is just one example of a broad phenomenon. It comes into high relief when you look at EROEI from a perspective of strict necessity. All kinds of interesting questions arise. Do the office staff of a drilling company actually *need* to drive to the office to produce the oil? Is the energy spent filing tax returns actually necessary to produce the oil? etc. etc. You really need to get a handle on the concept of "necessary". Otherwise, you're doing poli sci., not physics.