It's not the theft that's the problem with pay at the pump. The way gas stations mark up their convenience items inside I've heard it said that they make more from what you put in yourself than what you put in the car's tank. Pay at the pump cuts out those sales.
As for the self-checkout lanes, in general I love them but I try to use them with too large of orders. On many days it would be faster for me to go with a regular checkout because they don't have a delay to weigh every item. Unfortunately the store will have ten self-check lines open and only three regular lines.
Also produce is a crap shoot. I had some corn last week without a number on it, so I typed "corn" and two identical looking pictures of corn came up with different numbers. I asked for help and the employee typed in a third number instead of those two.
I use the self-checkout a lot since most of my visits to the store are for a small number of items. The Mrs. does the larger shopping.
Many years ago I worked a full service gas station and it became apparent that the cost for employees to pump gas and check oil was becoming prohibitive.
I have noticed that the products inside of the gas stations are much higher in cost and I rarely purchase anything other than gas.
I just don’t see pay-at-the-pump going away after so many users like the ease of not having to go inside - but I could be wrong.