I hold the opposite opinion.
Long ago my wife and I used to go to Food4Less, which is a grocery owned by Ralphs in California. F4L cost less because, while the registers were manned, you the buyer were the one who bagged your groceries. There's a similar thing at WinCo, which is in Arizona where I live. Unfortunately, the nearest WinCo is 30 minutes away. My wife and I got used to bagging our own groceries and were willing to do this to save a few dollars.
The majority of our grocery shopping is done at Walmart, which is less than 10 minutes away. Before they brought in self-checkout this particular store had a very bad habit of only having a few registers open. Your only choice was which long line to stand in. You could spend 10-15 minutes just waiting to be next. As annoyed as this made me I preferred cashiers until one particular incident.
Walmart does not accept Apple Pay. But they DO accept Walmart Pay. This is Walmart's own financial instrument where you open their app and use it to scan a QR code on the POS device. The code, the app and your Walmart account are all tied to a credit/debit card you have saved and your card gets charged. On the cashier's side it involves them hitting a series of buttons to prepare the system to accept a Walmart Pay transaction.
In this particular incident, the clerk was lazy and did not want to do her job. She flat out told me that Walmart does not accept Walmart Pay. I argued and she realized 'Oh crap, I'm dealing with someone who knows what they are talking about!' So, she made one half-hearted attempt at stabbing buttons and then told me 'It's not working'.
By this point, people behind me are starting to get pissed. I have become the customer I abhore, not ready, doesn't understand how to use the payment system, etc, etc. So I used my debit card and went on my way. But after that I decided to stick solely with the self-checkouts. If I have a problem, I can call a dedicated employee over.
I now refuse to further subsidize the continued employment of lazy and willfully ignorant employees by using a manned checkout.