I don't know about Sony, but I'm pretty sure Apple got the idea for their app store business model from Nintendo, who notoriously was the king of the walled garden business model. I'm pretty sure Nintendo took a 30% cut as well.
The only reason Sony is not charging exorbitant amounts (if they really aren't) is because they're in heated competition with Microsoft over being the preferred first release platform of popular games.
The only reason Sony is not charging exorbitant amounts (if they really aren't) is because they're in heated competition with Microsoft over being the preferred first release platform of popular games.