The mother in the story in question was emphatically not in a situation where even spanking was worthwhile. The kid was just not acting up in a way that even came close to meriting physical discipline. Bemoan the overly intrusive government (which definitely was present in "Revenants"), by all means, but it's not somehow impeding education or child-rearing that teachers, for instance, can't physically discipline children anymore.
And honestly, spanking is the easy source of discipline. It's fast, it's always available, and it certainly silences the children when they're being disruptive. But I have never seen anything that suggests that spanking is anything but the crudest and most harmful method of disciplining children. I think one study, ever, found positive emotional outcomes associated with spanking, and that was very carefully limited in the wording of the paper to mean rare one-time incidents of single slaps not hard enough to even leave a red mark, paired with conversation both prior ("Your father and I have decided to give you a spanking for these reasons...") and after ("We still love you, and we will never hit you without having these sorts of talks beforehand.")
So yeah, when I see people complaining about how terrible it is that spanking is being gradually lumped in with child abuse, I can't really feel very guilty for upsetting folks. It is very, very, VERY easy to abuse a child if you use corporal punishment regularly, and the benefits of spanking just do not seem worth it to me compared to the risks. In other words, yes, I see a difference between spanking and beating, in the same way I see a difference between green and blue Jolly Ranchers; the one is just barely tolerable while the other is an abomination, and it's still mostly the same stuff with only a thin line and sometimes blurred line separating them.