>but AFAIK there is no standard alternative way to calculate those "losses"

This isn't the problem at all. The problem is that they're calling them "losses", when they aren't losses at all. "Lose" is a plain English word with a very specific meaning: it means you no longer have something that you used to have. These companies never, ever "lost" anything at all due to "piracy". You can't use the word to describe "something you don't have, and never had at all, but which you should have"; it doesn't work that way.

If they used a different term, such as "unrealized revenue", then we probably wouldn't be having this discussion.