Why does everyone just assume that the software Google/Slack/other video/chat platforms use actually respect any of those settings? For all we know they simply

Why does everyone just assume that the software Google/Slack/other video/chat platforms use actually respect any of those settings? For all we know they simply mark this data as "deleted" and the GUI won't show it to you. In the USA there is practically no recourse users have if SAAS/PAAS simply decides to keep this data and not tell you about it. Google won't be investigated or punished, and you'll never get anyone on the phone to yell at about it. Taking them to court is like throwing money into a well. The truth is, if they decide to do it in secret you'd probably never even find out about it. Google is large enough to design its own hardware/firmware. They could probably implement this without many of their own internal teams being aware of it.