which is worse? someone with 2 items not using the self-checkout, or someone with 50 items using the self-checkout?
Let's be careful who we demonize.
this may be a salina/dumbass-centric thing, but i swear that 9 out of 10 times i can make it through the standard lane quicker with my little basket than i can through the unwashed dumbasses cramming through the express & self-checkout.
am i a demon? 
No, the express lanes are huge wastes of time because stores refuse to police their own policies. The express lanes are shorter and people have way too many items for them, so it takes twice as long for them to check out.
Most stores have enough self checkout lanes so that you hardly have to wait in line at all, and when there is a wait, you aren't just waiting on one person, so even if you have some old geriatric who has to go across the store to find somebody to give her check to, odds are a different lane will open up pretty soon.