Generally, a female porn actress will make less than $1,000 for a standard scene and a few $100 more if it includes anal. Male porn actors make around $200-300 for a scene.
Also, it's not "an hour or so of work". A scene can take up to 6 hours to shoot, and a full day never includes more than two or three scenes. There's also time spent pre- and post-shoot.
Of course, the famous actor will make more, but just as in every other industry, there are very few of them compared to the total.
The worst part is that it's a lot of work to find constant work unless you have a really good manager or you're famous. Sure, the hours are short, but I found that having stable hours and not having to live shoot pay check to shoot pay check is preferable, even if it's a considerably lower hourly wage.
(Much like contract programming work!)
This is why individual contractors charging $100-200 an hour are not actually making $250-500k a year.
I'm not saying you're wrong about the rates (and it does seem like they've dropped a lot lately after looking into it), but I'm either grossly misremembering or we paid a premium for our talent. I believe it was the latter, because the company definitely liked to spend money.
Edit: Interestingly, whereas open-source code expands the market (and rates) for programmers, open porn destroys the market for porn stars...
Has this been proven?