I think maybe you're thinking it in the wrong way? If A immediately owns up and apologizes, B not getting into a frenzy of swear words is not only good for A, but it's good for B, too (unnecessary stress and getting-worked-up is probably not really good for us!). Clearly if they were still upset (despite the apology), they might still feel the need to yell and vent a bit, and if they do, perhaps they will. But if they don't, then likely the acknowledgement of fault and apology has been appreciated, and B has gotten out of it what they need to.
For something like knocking over a coffee, certainly, the knocker owes the knockee a new coffee, and acknowledging fault and apologizing is the first step to getting there.
(B retaliating by knocking over A's coffee is always going to be unproductive and childish, even if A is unrepentant and rude about it.)
I agree that just saying that you own your mistake isn't enough; owning it means doing the best you can to make amends. But sometimes the person you wronged is fine with just an acknowledgement and an apology. For example, if someone knocked over my coffee, and it seemed like a genuine mistake (that is, it wasn't because the person was being careless or negligent), I probably would accept an apology but decline a new coffee. The apology would be enough for me. Not saying that it would be for everyone, but people are different.
A caring about B is a good point. If A thinks to themself, "Crap, I effed up. I should apologize. B will be mad, what can I do to make B feel better? I could buy them a coffee", that's pretty good. If A thinks, "Crap, I effed up. I should apologize and reconsider wrestling near people's desks", that's also pretty good. Ideally, both the reflection and the coffee would be nice. If I had to choose just one, I'm leaning towards the latter as owning the mistake more than B being made whole with coffee, but that's debateable (and might be where we differ).
If it's, "Oh, B will be mad, what can I do so that this doesn't take too long? I could apologize and buy them a coffee", it feels less right. It inches toward that phrase that goes something like "the fastest way to get someone to shut up is to agree with them." It might be true in a practical sense and yet it's woefully sociopathic.
For something like knocking over a coffee, certainly, the knocker owes the knockee a new coffee, and acknowledging fault and apologizing is the first step to getting there.
(B retaliating by knocking over A's coffee is always going to be unproductive and childish, even if A is unrepentant and rude about it.)
I agree that just saying that you own your mistake isn't enough; owning it means doing the best you can to make amends. But sometimes the person you wronged is fine with just an acknowledgement and an apology. For example, if someone knocked over my coffee, and it seemed like a genuine mistake (that is, it wasn't because the person was being careless or negligent), I probably would accept an apology but decline a new coffee. The apology would be enough for me. Not saying that it would be for everyone, but people are different.