Stock options are probably a better deal. There's accounting BS with options, but FAR less than you would see with residuals.
But for a private company, where are the options are essentially a lottery ticket, I think a decent number of folks would choose residuals.
Also, they could just rewrite the sections of code that are expensive and nuke their costs and your residuals at any point. Unlike a brand or whatever, it’s trivial to redo as it’s not user facing.