Why can't the Vita share screenshots automatically?

Sony has had a bit of a hit with the PS4's Share button, which makes me wonder why, if the Vita can take screenshots of games in action, why there isn't an auto-share option to post them to Twitter or other social media.

After all, if the Vita needs promoting, then what better way to do it then sending cool shots of games in action to millions of people, for free. It can't be too hard to add an option in Settings to autoshare screenshots, and the Vita has a Twitter app anyway, so getting the details, or adding them to the account can't be too hard.

You have to wonder, since Sony was clearly working on the PS4 during the Vita's inception, why they didn't think about screenshot sharing as a key feature, rather than the crappy Near and goods trading experiences that few have ever used.

Is it too late in the Vita's life to add this feature? It probably won't make any difference, but I know I see lots of PS4 shots and go "cool", so why not do the same for the Vita? I'm guessing video sharing is a bit beyond the hardware, but I'd be delighted to use a screen sharing feature.