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.
Not just YOUR server admin… Anybody capable of setting up a Lemmy instance has access to this data.
While most people at discuss.tchncs.de may assume that /u/milan and /u/erAck can see this type of thing, it may not be obvious that so can /u/muddybulldog@mylemmy.win or /u/ruud@lemmy.world and every other instance admin in the world can, as well.
Is that what you found out during your experiments?
That seems like a really inefficient and useless implementation to have all instances provide those details to one another, when every instance can simply keep track of it for their own users and pass along the total number.