I'm assuming stock grants or residual payments are never part of the deal either, right? That's just completely exploitative of their dev talent.
Even $50k for a senior employee for years of working hard overtime is a joke compared to any other industry.
I've aware of royalties in some really, really rare cases(think north of 10M sales, in the < 1% of game sales category), but even in that case from what I heard the publisher had a cap on the upper limit per year in the contract.