This is weird, because I have a sort of similar reaction, but at a much lower intensity. The self-serve McDonalds machines were slow, but comprehensible to me. Likewise, self-checkout is occasionally frustrating, but generally much faster than waiting for a human cashier in my experience.
It's more that I couldn't be bothered to figure it out since the cashier is faster. It's the same thing at the grocery store. If I have simple items and the line is more than 3 ppl long I go self checkout but often there is a line for that and it moves at roughly the same speed (even though there are 4 stands). The bigger problem is bulk items, fruits, vegetables and alcohol, those take a lot of time to enter into the system. Way too many menus and buttons and very high error rates.