Providing translation on it's own i not piracy in any way shape or form. It's once you put those translations into the actual work and start distributing that, that it becomes piracy. This is why most scanlation qualifies as piracy and most game translation does not.
Has it ever occured to you that these game translators are upset, because their patches are used for the purpose of piracy without their permission? Making a lanuage patch does not constitute piracy. Stealing said patch and applying it to illegal roms to sell them, does.
Also actually a lot of scanlation groups take projects down once they become officially licensed. Not only because they're afarid of dmca takedown notices or cease and desist letters (although that certainly plays into it), but because they want to see the original content creators get their money just as much as you do.
Of course, this does not realy apply to mega series like One Piece where the fan translations are more about speed. You can read each new chapter/watch each new epidsode almost immediately after it comes out in japan, with fansubs and scanlations instead of having to wait months, sometimes years for the next official release. Like in many cases, this kind of piracy is more about convinience than anything else.
The reason why piracy is bad though, is the theory of the lost sale. in these cases, especially scanlation where a work is in a laguage a majority of the people neither understand, nor will ever get the opportunity to learn, there is no lost sale. If a series doesn't get brought over officially, then it has no market to loose.
In fact, in these cases, it has market to gain. Publishers actively scout the scanlation scene for new series to publish, wich is the smartest thing to do. A lot of these people using fan translations jump at the opportunity to get a physical copy in their own laguage (or at least one they can understand). Many of these people do want to support the content creators and even go so far as to import japanese copys they can't even read because of it.
I know I did that when I was younger, I bought entire series twice, once in japanese and once when they finally did get brought to the west, to support the western release and show interest. Some things, I bought three times because we've had our own Manga magazines around here, modeled after the japanense system, with monthly releases and tankoubons to follow later. Even though I actively pirated their stuff, these content creators actually made more money off, me than any random japanese person. And the thing that allowed for that? Piracy.
Yes, there's always going to be jerks who won't pay for anything (not a lost sale if you ask me,but that's admittedly debatable), or just plain poor kids who can't afford to pay (definitively not a lost sale), but overall in this specific case piracy actually helped japanese content creators more than it harmed them. It helped to actually carve out a market for them to take advantage of. Piracy can take risks, major publishers would never take, because they don't have monetary loss to fear. If it turns out to be a big success the Publishers can swoop in and still take the bulk of the profits.