How do we know today is any different than those examples above?
The practice of science, which is not an end unto itself, is possible to indulge in because we each have a chance at examining data and methods. When those are restricted or changed without reason, that is another data point. We no longer need to, nor do we, rely on lobbyists who write legislation and policy.
Why do you think things are so much different today than they were just a few decades ago when the science in regard to sugar was corrupted? The corruption was successful then, and things aren't that much different today. Do you honestly believe that in 50 years time we wont look back and see at least one thing that was purported to be scientifically proven true, subsequently falsified?
Nothing has changed at all, really.
That's exactly right. So we're equally vulnerable to corrupted science as all the people before us who fell victim to the examples listed above.