One-Click Purchasing

Given Amazon's popularity with the one-click purchasing, when should we expect social media platforms to implement that feature? For instance, when an Instagram ad pops up, it could have the option to "buy it now." It seems like the biggest hurdle to conversion of a sale on social media is getting consumers comfortable to purchase items directly through the app (opposed to searching for that item online at a particular website). It seems that this functionality would result in higher conversion rates.