Edit: obligatory explanation (thanks mods for squaring me away)…
What you see via the UI isn’t “all that exists”. Unlike Reddit, where everything is a black box, there are a lot more eyeballs who can see “under the hood”. Any instance admin, proper or rogue, gets a ton of information that users won’t normally see. The attached example demonstrates that while users will only see upvote/downvote tallies, admins can see who actually performed those actions.
Edit: To clarify, not just YOUR instance admin gets this info. This is ANY instance admin across the Fediverse.
You were saying in the example of the government requesting the data. That’s not any different for reddit or Lemmy. If anything, it would be harder to get from Lemmy since it’s decentralized. And reddit is known to comply with government warrants.
A warrant is still more secure than public access.