They don't have to. You can disable it at https://myactivity.google.com
Google's always mining data behind the scenes and gapps are constantly phoning home, your "opt-out" preferences are meaningless.
That excuse made sense in a time where public trust in these companies was justifiably high but it's turned into a situation where the major tech giants have the power to become a modern day Stasi on steroids (and increasingly show their willingness to play that role). We had to place enormous trust in these company's ethics (mostly on a subconscious level as they all used to go to great lengths to afford us the ability to implicitly trust them) in order for the smartphone/mobile revolution to occur. Now that these devices are a necessity in modern society, they've all dropped the pretenses that allowed us to trust anything to do with the information they're collecting.
We're living in a cyberpunk dystopia and I don't see an easy way out.
Workaround:
1)Install F-Droid (f-droid.org) 2) Install Yalp Store from F-Droid
Not that I have any insider information but a while back someone made a post on reddit about what baffles them about their work and they had a job where they basically listened to very short voice clips and saw something on the screen and they had to decide whether it was the right word on the screen or not.
In case you weren’t joking.
What I don't understand is why they have to store voice recordings instead of deleting them once they understand the vocal command. There could be a number of reasons and I don't like any of them.