system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] Why doesn't anybody seem to care about the temporal prime directive?

While the "normal" prime directive is a enforced strictly (with some exceptions), Starfleet is pretty loosey goosey when it comes to interfering in past events. I can count numerous times when the Enterprise-D alone has meddled in history, not always in a way that was inevitable or necessary for survival or to complete the mission at hand (taking freakin' Mark Twain for a tour on the ship in Time's Arrow, for example). Doesn't anyone seem to mind it? Due to the complexity temporal physics, it can be argued that this type of meddling could be quite dangerous, even more so than violating the "normal" PD.
gpt
One of the problems is that Star Trek never really defined how time travel works. Do you need to worry about killing Hitler, or will *something* always prevent it from happening before his recorded death, either via your efforts or that of the time cops from the Future Federation?

Just claiming that traveling back in time can't affect the future is paradoxical if one assumes that there is only one timeline. Either you *always* went back and meddled or you *never* did. Further, with this model, you *can't* change anything that you'd notice, because you are a product of history. If you remember Hitler being killed in 1939, then you'll never travel back in time to alter that fact.

The closest this came to happening was the episode "Yesterday's Enterprise." Only a higher-dimensional being, Guinan, could even suspect something had altered time, and in the end, she was the only one who knew anything happened (until Denise Crosby showed up again).

In order for you to remember why you traveled into the past to change something, you'd have to forge a new timeline when you arrived. You could alter whatever you wanted willy-nilly, since you've basically entered a new universe that branched off from your home universe the second you showed up.

Now, what I'd assume the Future Federation would have to be is some group that exists outside of spacetime. In essence, they'd have to observe from another universe somehow, so that they aren't subject to the causality changes. There's a series of Asimov short stories about that, where a group of volunteers (since you're basically signing on to *technically* not exist due to alterations in history) will study the timeline and decide what events, starting with the founding of their organization, results in the best possible outcome. Then, they work to steer history towards said outcome, able to watch and remember changes due to being outside of the universe where they take place.