Scale is a big part of it.
Every minute, 500 hours of video are uploaded to YouTube.
Even Google can't afford to run the biggest baddest model on every single one of those hours.
I thought so, too. But they also let you create AI dubs of your videos into an arbitrary number of languages?
Though they do have the money to generate terrible TTS audio for many videos. And since google can't fathom a person knowing a foreign language, use those automatically without warning.