> So I'm wondering if the services actually have some sort of archiving requirement for law enforcement purposes? Maybe for a certain number of years, they have to save your data or something like that?
Apart from a handful of specific cases like financial data, the US has no general data-retention laws. You can delete stuff aggressively as long as it's based on a consistent archival policy, not one-off deletions where you risk looking like you chose a particular thing to delete to hide evidence.
You can tell this is possible in practice by looking at how common it is to have aggressive permanent-deletion policies in corporate email, at least outside of tech. A number of big US companies automatically delete read emails in employees' inboxes after N days (with N ranging from 7 (!) to 365), unless the employee specifically takes action to refile the email into a project folder with a different per-project retention policy. The goal of those policies is to reduce companies' exposure to fishing expeditions in future lawsuits by just keeping less email around. To make that effective, the policies really do delete the emails, including from any backup systems.
Given that they have figured out how to perma-delete their own old email, I believe companies could really delete user-deleted content, perhaps after some specified period of time, if they wanted to. But unlike with their own internal emails, they don't have the same incentives to be aggressive about purging that stuff from their servers. If anything, they have the opposite incentive, to keep as much user data around indefinitely as possible.