For 1, my configuration of zsh solves the problem and avoids surprises by marking pasted shell code and letting me review it before running it, even if there are several lines. This is great for just pasting stuff from the internet and adapt as I wish without having to retype the entire thing or use an editor. I think this is a default behavior in oh-my-zsh.

Actually, my zsh config mostly behaves like fish with great completion, syntax coloring and sensible history handling, with zsh syntax which is close to bash. So I can copy paste stuff from the internet and reuse my knowledge from the time I used bash because it was the default, and still leverage the improvements brought by zsh.

I don't understand 2.

For 3, of course you should understand what you run, but I don't want my tools to get in the way. My tools should allow me to do what I want, not prevent me from doing something for technical reasons. This is a question of education. If people want to run something without understanding it, I bet they will type it blindly, if they can't copy paste it. They will just be slower at running things blindly, leading them to a disaster just a bit slower. Please let me not lose my time even more when I cause disasters.

(Yes, true, retyping stuff forces your more to think about it, but I already review the things I paste into my shell)