Only if I have like 5 items or less. I'm in the USA and it doesn't matter if I'm at Walmart in Arkansas or a grocery store in L.A. If I've got a shopping cart with $250 of groceries, it doesn't make sense to use the self checkout. It's faster to have me tossing stuff onto the conveyor belt while the cashier is dropping the items into the bags on the carousel thingy and then the other employee is transferring the bags to the cart.
I will only use self checkout at the supermarket if I have a small order, for the weekly grocery shop I always line up at the manned checkout.