I guess it depends on where the Self Service Kiosks have been deployed - I can Scan, Bag, Pay, leave in < 60 seconds with 6 items in my basket. Honestly, the hardest part is opening a hole in top of the bag that I can put stuff in.
Concur - if I have a cart, probably would use a checkout person - but, when you get used to buying stuff from the store 1-2x a day, you rarely have a large load.