I really want Google to advertise this...

Ie. I want them to commit to "No human who works at Google will ever see your email or photos without you knowing about it". And then splash that statement all over TV ads.

Set up some system so every time an engineer sees user data, the owner of that data is sent a notification (and there are legit reasons for that, like investigating a bug a user has reported). It doesn't need to be for every kind of user data, just the super sensitive ones like the text of emails.

While it doesn't work for consumer accounts, https://support.google.com/a/answer/9230474?hl=en already exists, and https://cloud.google.com/cloud-provider-access-management/ac... goes further, requiring your consent before access. Although it doesn't work for certain legally mandated things