Relatedly, Maps shows me when a location is likely to be popular vs unpopular. I have to assume that's based on the location history of everyone using Maps - seeing how long they spend in a place and at what time. But what percentage of Maps users are aware their information is being used in this way? I doubt the number is high.
Also, now I come to think of it, Google search itself. It shows different results sometimes when I'm logged in vs logged out, but it's not clear why. And I don't recall ever being asked if I wanted, say, my browsing history to influence future search results. It just does. Somehow.
It sounds like you want something different than transparency about when information is collected, but instead you want transparency about what information is used to give you a specific feature.
For example, you opted into location history a long time ago (likely), should Google again ask for your permission every time they add a new feature that takes advantage of your location history information? (assuming said features don't affect the privacy of your data)
That seems like a very strange onus.
Not OP, but - sure, why not? It would be really nice to have that. Especially if it wasn't the meaningless kind of transparency, "we use your location data as well as past interests to provide this feature", but something concrete - "we use regular GPS/cellular/wifi location updates to determine places where you've stayed for longer and correlate that with your recent searches in Google, as well as visits to venue sites that use Google Analytics".
(Personally, I'd be fine with such concrete announcements popping up the first time you use the app after a new feature was added, and if a feature is something one might want to not use, I'd be happy with it being opt-out. Just don't surprise people with application suddenly doing new things by itself, without much prior warning.)
Because if we lived in that reality, you'd end up complaining about how Google was sending you unwanted marketing emails about new features multiple times per week, and I'd be arguing that they were emails discussing new privacy updates.
Not to say that no one would want that, but as someone who does, by way of working at Google, more or less get emails similar to the technical descriptions of newly released features you want, very few of them are relevant to me.
Maybe they'd combat the perception I have of Google - that they just do UI redesign every couple of months, which more often than not lose useful features than add anything of value.
You say you get lots of those e-mails internally; I'd love to know where Google is actually adding all those features - because it definitely doesn't seem to be Inbox, or GMail, or Google Maps.
Weird, I'm pretty sure with my new Android phone, upon booting it up for the first time, I had to opt in to location services and a little popup explained exactly what it was doing.
This is based on the location history of everyone using Android. Its the Google Location Services requests going back and forth all the time that tells them where people go.