Meanwhile a friend who took part in the recent Writers Strike mentioned how his friends, with "normal" jobs, questioned by writers (and, by extension, all creative types) have the audacity to think they should be paid "more than once" for their work. This is all part of the same mentality, the idea that whatever you do your employer gets to make the money off it because it's his risk and he's paying you, and you knew that going in.
Well, there's an easy enough answer to that one: if you believe that you're an idiot.
Creative freelancers are their own employers. Like anyone else the deals we make during our active earning years are the deals we live off the rest of our lives. "Normal" jobs have retiree health benefits, pension plans, etc. We get none of that, unless we belong to a strong union with the muscle to provide health care, and that's pretty much only the WGA and only if you've worked in film or television a sufficient amount. But more and more people at "normal" jobs are retiring only to find their health plan has been cancelled or whatever their pensions were invested in have gone belly up, and suddenly they find themselves staring down crippling medical bills or working as an 80 year old greeter at Sam's Club to make ends meet. Most of us don't want to be greeters at Sam's Club so we try to set up arrangements to keep money coming in, especially on things we created. Because that's how it's done these days in this field; things like royalties for exploitations of works -- even if those exploitations didn't exist at the time the work was done -- are now an established element, certainly of the comics business, and of the book business for a considerably longer period. It's our version of a pension plan, as subject to a publisher's ability to profitably exploit a property as any employer pension plan. It has been the usual policy of comics companies to not include old deals/creators in new payment programs, but there's absolutely no good reason why the Siegels & Shusters shouldn't get, at minimum, the same creator compensation deal that the creator of, oh, Spoiler gets.
In the Siegel estate's case, they weren't trying to get anything they're not entitled to under the law, as Larson's opinion makes evident.
Look at it this way: money is how we measure value in our society. With media properties, it's often difficult to determine value up front, and if value were determined up front there would be almost nothing put into production in any medium, because full payment of possible value would be almost prohibitive. Look at the money machine STAR WARS turned into; nobody guessed that in advance, which is why it had no notable stars (except for Alec Guinness and Peter Cushing, and neither were exactly the king of Hollywood at the time) and a relatively low production budget. If George Lucas had known what revenues the property would eventually generate and had asked for all those up front, it never would have gotten made because no one could have afforded to meet the price.
So in media the initial payment isn't the total payment (though it sometimes ends up that way), it's the down payment. Publishers and producers don't "buy" properties so much as place their bets; they secure the cooperation of talent. "Value" isn't determined in advance, but as it accrues, and as the established value of a property increases, so does the amount paid to those who generate it, according to whatever contract is in place. There is the common belief, for whatever reason, that the publisher/producer is the one taking the risk and therefore the rightful end point of all profits. But by choosing to work with them, and the operations they represent, we take a risk too. We are risking that they will make the right decisions along the way to public release, that they will be able to intelligently and fully exploit the property for the fullest short-and-long term profitability. And you know what? More often than not, they don't, even though that's their job. It's only not our risk if we're not getting paid more as the property is more successfully exploited.
Because that's the game.
Your job doesn't work like that? Don't come crying to me about it. Why doesn't it work like that? Why don't you insist on profit sharing? Many companies do profit share; others, while they claim all rights to technologies or other profit streams developed by their employees, also provide additional payments for "the same work." Ever heard of Christmas bonuses? Incentive bonuses? Law firms frequently pay bonuses to lawyers who bring large accounts in, or win large payoff cases. Some companies pay royalties to employees whose ideas continue to generate revenues for the company, for as long as the ideas generate revenue. Nothing in the freelance setup is unheard of in "normal" jobs.
There's a line in an old Bob Dylan song that goes
"And you ask why I don't live here?
Man, how come you don't move?"
Well? How come? Because there's a Sam's Club right around the corner...