The average advance on a book is very roughly $10,000. The Screenwriters Guilds says the minimum that Hollywood can pay a screenwriter is a bit over $100,000.
That's a factor of ten.
And if someone wants to take my copyright from me, yes my agent better damned well get me more money for that.
Yes, but averages mean absolutely nothing. Screenwriters don't earn royalties, but novelists do. Even without royalties, no one ever earned a penny because of what the average writer earns.
First, you can write and sell all sorts of screenplays that do not fall under the guild minimum. Second, last time I checked, the guild minimum through 2014 is,
with treatment, a bit over $66,000 and there's no guarantee at all that you will get more than a part of this. Anyway, the treatment itself earns a minimum of $29,457, the first draft of the screenplay gets,$25,601 minimum, and the final draft gets $9,955 minimum. The writer may not get to do all three parts.
It is, in fact, quite common for one writer to do the treatment, another to do the first draft, and yet another, or a team or others, to do the final draft. Teams and rewrites are big in Hollywood.
And, of course, these days the screenplay is often written, and the movie well under way, before Hollywood even gets involved.
A lot of other factors also work into this, and you may sell more than one screenplay, and maybe a big bunch of them, before you quality for the guild minimum. I know one screenwriter who sold an original screenplay a couple of years ago for a flat $100, and another who sold two for a thousand bucks each.
And who's going to pay you a hundred grand for a movie that has a total budget of two hundred grand, or less?
And copyright has nothing to do with it. Copyright with screenplays has nothing in common with copyright for novels, short stories, or anything else. Just what would you do with the copyright, if they let you keep it?
You don't sell the screenplay until
after someone intends to make a movie out of it, and neither you, nor anyone else, is going to make the exact same movie using the exact same screenplay, ever again. It isn't a matter of selling copyright, it's a mater of that screenplay being useless after it's turned into a movie.
Until a movie is in the works, you simply sell an option, and with the option, you still have copyright.