In those stores that have the option, I pick self-checkout or cashier based on which has the shortest lines. I almost always do the self-checkout at Home Depot, as it turns out. The Target by our home recently started a self-checkout and I have used that several times. The two Safeway stores by our home recently removed their self-checkout; I asked an employee and she said it was due to theft.
Conversely, I always decline to use self-checkout. It's obviously a cost saving to the stores, I get that, but it's also another increment in the elimination of jobs that some people may need, and not be qualified to do anything more difficult. While I like prices to be as low as possible, I am not in favor of replacing humans with machines on a wholesale basis, and so I decline to support it.
Yes, I know that modern cars are largely built by robots, and most modern firearms are produced with CNC machines and that the machines can do the work better and more consistently than humans. That's a trade-off, and I still wrestle with it. Replacing checkout clerks with machines doesn't (to me) offer any compensating benefits. My late wife was from South America. There is a chain of large stores in her country that are sort of like Super Walmarts -- they sell everything from small hardware bits to produce, bread, and foods. They don't have self-checkout. (At least, they didn't the last time I visited, with was in 2014.) The store that I went to most frequently had 74 checkout lanes. (They were numbered, so I didn't have to count.) On a typical day, at least 70 of them would be open and there would never be more than three people in line for a cashier -- usually not more than two. I found it very civilized and refreshing, especially compared to here, where a typical Walmart may still have ten or twelve conventional checkout lanes but most times only two or three are open and the customers at each are lined up six to eight deep. I know that Walmart is trying to force me to use the automated lanes, and I don't choose to succumb.
