Amazon Shorts needs SF back catalogues

Searching for stories in the previous post something struck me. I'd pay a few pence to buy some of those stories. I checked on Amazon Shorts to see if they were there, but no, it only seems to publish new stories. Presumably there are publishing copyright issues? But if Apple can overcome the reluctance of record companies with iTunes then why can't Amazon do the same with publishers? Imagine the back catalogue short stories of Asimov, Heinlein etc etc online and for sale for $0.49 per story. Would they sell a lot? I think so.