The dictionary definition of penance, copied from Google, is
voluntary self-punishment inflicted as an outward expression of repentance for having done wrong.
Well, I would look to a Catholic definition of penance, not necessarily a dictionary definition (they could be different), but I do see, from your explanation, that purgatorial penance is not the only kind of “penance”. I knew that, I just had a kind of “tunnel vision”, reasoning that since Protestants don’t have a concept of purgatory, nor of having to make some kind of tangible satisfaction to Almighty God for the punishment due their sins — since “Jesus did it all” — they then do not do what we would call “penance” for any other reasons. Clearly they do, at least in some fashion. I don’t think they offer their sufferings and sacrifices, putting them in some kind of celestial “penance bank” to atone to God for their sins and the sins of others, but they do have some kind of at least partial concept of penance, even if they don’t call it that.
I don’t deny for a moment that penance can be offered and performed for reasons other than mitigating one’s own just punishment that will be exacted either in this life or, failing that, in purgatory. Catholics can and do offer all sorts of atonement, penance, call it what you will, for the sins of the whole world and the sins of others, both living and dead. We have a very elaborated concept of “consoling God” that, if it exists in Protestantism, I’ve never heard of it. But I do think that all Christians have a concept of “the wrath of God” and that He can, and may, punish the world in general, or evil societies in particular, in the “here and now”. We need look no further than Sodom and Gomorrah, or the whole world as in the case of the Flood. Even no less an authority than Jack Chick’s publishing house
assures us that the next worldwide chastisement will be by fire.