[Eridrus]

In general, SWE/SRE do not have access to user data. SWEs just have no prod access at all, and SREs generally only have the ability to run signed binaries with code that has been code reviewed and submitted, though there are obviously break glass features with auditing. Though I am not super familiar with them.

ML is where things tend to be a little bit more grey overall since being able to look at data is very useful for development, so some things are scrubbed for PII, but then accessible in some form. But for things like GMail or Photos, I would assume nobody (including ML engineers) can read your data as these are basically impossible to sanitize.

Some products have systems train ML models without engineers seeing the data, e.g. spam filtering, even when the underlying data is considered sensitive.

[hansvm]

Basically all the data is available with no oversight if you ask permission and have some allusion to a relevant $JOB reason to need it.

The fairly recent case of people's private conversations being shipped out to basically unvetted contractors for labeling and analysis (and subsequently leaked) should serve as sufficient evidence that "shit happens," and if private conversations without having even initiated an interaction with your Google devices are being tossed around and leaked, forgive me if I don't believe that when producing the tagging, timeline, and album features in Google Photos there wasn't some underpaid, unwatched contractor snooping through my photos without my permission.