This seems more fair. But it is weird, because thinking about it, isn't buying N units of work the most fair pricing scheme? I didn't have the same gut reaction to Amazon's Lambda service.
Perhaps it is that we know the article limit isn't related to any real-world costs that make the difference.
It's fair but the worry comes in with what happens if I run out of units of work and send a new article. Does it reject the article and I miss out? Does it charge as and when I send an article[1]? Do I get charged extra for unexpected usage?
If I have to ponder any one of these questions I'd just switch to a different app, there's a fair few that provide this functionality
[1] In this case the main worry is what if I accidentally somehow send every tab I have open to this service through a bug or something? Do I pay or does the app maker take one for the team?
As someone who would also like this sort of app, I can do this completely free with Pocket on my Kobo reader. I don't know why anyone would pay for this service.
This sort of thing is a one off purchase (if my device does the work) or fixed monthly fee (if your servers do the work)