Ask HN: Why do iPhones not yet have transcribed voicemail?

Doesn't Apple have the technology to do this post-Siri? I know there are other apps you can use to make this happen like Yap, but shouldn't a company like Apple at this point have that built in for convenience? I would like to just be able to go to my voicemail and either play it or read it--with the optional setting to have it texted to me automatically.