You are still putting trust into the fact that the groups/experimenters are actually independent. Unless you have personally verified every experiment, you are still putting trust into the fact that others have done the work as they claim. What you are doing is being _pragmatic_ about your trust. You have a level of trust that is acceptable.

The reality is that we all are trusting "science" to one degree or another. I absolutely agree that all experiments should be repeatable and independently verifiable, but in the real world science (in my opinion) very much depends on trust. We don't all have time to verify every experiment.