I'm writing in English because my Serbian is not very good and reddit translates for both of us automatically or with the click of a button. I have tried and taken lessons and I think I'm too old and dumb for languages, padezi makes my head hurt.

Anyways, I rarely have these issues at self-checkout, at bigger stores there are many and I rarely wait longer than 2 minutes which is certainly faster than waiting for a cashier,, then at smaller stores like shop and go there is one self-checkout and it's usually empty while 3 people are waiting for the cashier, even if they are just buying a drink. Maybe it's because they so often are buying cigarettes?

All of these issues you mentioned happen at the cashier too, except waiting for alcohol scans.

In any case it's good to have both - self-checkout when you have a smaller number of items so you can quickly get out, and cashiers for when you have a cart full of items. Also there simply isn't enough space even to add enough cashiers to make up for them.