Protecting jobs is the stupidest possible reason to be anti self checkout. I don't care much about the other points but that one I find really stupid. I guess we should also remove all automation from manufacturing and use hammers and nails to build cars as well. Let's also destroy all calculators since we can just go back to people crunching out numbers on paper.
Look at all these poor women that lost their jobs because of big calculator.
The thing is you're distributing that time onto a lot of people. Instead of a person having to sit at the register 24/7 now people spend 1 minute longer at the store because they have to scan stuff themselves, which is negligible. In fact, you're (or at least I am) almost always faster at shopping because now you don't need to wait for a register to open up. Now you have an entire human being that's free to do something else.
Another important fact is that for me at least the difference between when a cashier checks out goods for me and when I do it is maybe 30%, which again doesn't count the fact that you don't have to wait for a free cash register or the wait is much shorter most of the time.
Another thing it helps with is when you have a grandma fidling with her coins trying to find exact change for 5 minutes blocking everyone behind her. You can just go to a different self checkout instead of waiting for the single open till to free up.