> For example, if 5 year old runs out into traffic on a busy road and you pull them back, which form of discipline is more likely to negatively incentivize the impulse to dash into the street to get a penny?

I'm glad that you brought up this example because it's the one context in which I think spanking can be acceptable (needing to shock a child from something they were about to do that could have endangered themselves or others). I'm not a parent and not sure I wouldn't try to find some other approach but I can see the strength of the argument here (where I can't see it for other uses of corporal punishment of children).